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Solution NMR conformation of glycosaminoglycans. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 114:61-8. [DOI: 10.1016/j.pbiomolbio.2014.01.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 01/10/2014] [Accepted: 01/17/2014] [Indexed: 11/18/2022]
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202
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Rashid Q, Abid M, Jairajpuri MA. Elucidating the specificity of non-heparin-based conformational activators of antithrombin for factor Xa inhibition. J Nat Sci Biol Med 2014; 5:36-42. [PMID: 24678194 PMCID: PMC3961949 DOI: 10.4103/0976-9668.127282] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Introduction: Antithrombin, the principal inhibitor of coagulation proteases, requires allosteric activation by its physiological cofactor, heparin or heparin sulfate to achieve physiologically permissible rates. This forms the basis of heparin's use as a clinical anticoagulant. However, heparin therapy is beset with severe complications, giving rise to the need to search new non-heparin activators of antithrombin, devoid of these complications and with favorable safety profiles. Materials and Methods: We chose some representative organic compounds that have been shown to be involved in coagulation modulation by affecting antithrombin and applied a blind docking protocol to find the binding energy and interactions of the modified (sulfated) versus unmodified organic scaffolds. Results and Conclusion: Increased sulfation plays a key role in shifting the specificity of organic compounds like quercetin, diosmin, rutin, mangiferin, isomangostin, Trapezifolixanthone and benzofuran towards the heparin binding site (HBS). However, in hesperetin and tetrahydroisoquinoline, sulfation shifts the specificity away from HBS. We have further tried to elucidate changes in the binding affinity of quercetin on account of gradual increase in the number of hydroxyl groups being substituted by sulfate groups. The results show gradual increase in binding energy with increase in sulfation. A theoretical screening approach is an ideal mechanism to predict lead molecules as activators of antithrombin and in determining the specificity for antithrombin.
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Affiliation(s)
- Qudsia Rashid
- Department of Bio-Sciences, Protein Conformation and Enzymology Lab, New Delhi, India
| | - Mohammad Abid
- Department of Organic Synthesis Lab, Jamia Millia Islamia, New Delhi, India
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203
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Subconjunctival injection of low-molecular-weight heparin-taurocholate 7 inhibits corneal neovascularization. Cornea 2014; 32:1488-92. [PMID: 24055905 DOI: 10.1097/ico.0b013e3182a48009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To evaluate the effects of a subconjunctival injection of low-molecular-weight heparin-taurocholate 7 (LHT7) on corneal neovascularization (CoNV) in rats. METHODS Twenty-four Sprague-Dawley rats were divided into 4 groups of 6 animals each. Corneal centers were cauterized by the application of a silver/potassium nitrate solution for 8 seconds. Either 0.02 or 0.04 mL of 25 mg/mL of LHT7 (low- and high-LHT7 groups, respectively) was subconjunctivally injected on days 2 and 4 after the cauterization was done; 0.02 mL of 25 mg/mL of bevacizumab was injected into rats in the positive control group, with normal saline (NS) being administered to a negative control group. Digital photographs of the cornea were taken 1 and 2 weeks later to calculate the percentage of CoNV using the area of the neovascularized cornea. To compare the differences in CoNV between weeks 1 and 2, the change in CoNV was calculated by subtracting the percentage of CoNV at 1 week from that at 2 weeks. RESULTS The percentage of CoNV did not differ among the 4 groups either 1 or 2 weeks after the cauterization (P > 0.05). In all groups except the NS group, the percentage of CoNV significantly decreased at 2 weeks compared with that at 1 week (all P < 0.05). Moreover, the changes of CoNV in the high-LHT7 and bevacizumab groups significantly decreased compared with that in the NS group (all P < 0.05). Two corneal stromal hemorrhages occurred, 1 in each LHT7 group. CONCLUSIONS Despite complications, including corneal stromal hemorrhage, subconjunctival injection of LHT7 attenuated CoNV after chemical cauterization.
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Kassaar O, McMahon SA, Thompson R, Botting CH, Naismith JH, Stewart AJ. Crystal structure of histidine-rich glycoprotein N2 domain reveals redox activity at an interdomain disulfide bridge: implications for angiogenic regulation. Blood 2014; 123:1948-55. [PMID: 24501222 PMCID: PMC3962167 DOI: 10.1182/blood-2013-11-535963] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 02/02/2014] [Indexed: 11/20/2022] Open
Abstract
Histidine-rich glycoprotein (HRG) is a plasma protein consisting of 6 distinct functional domains and is an important regulator of key cardiovascular processes, including angiogenesis and coagulation. The protein is composed of 2 N-terminal domains (N1 and N2), 2 proline-rich regions (PRR1 and PRR2) that flank a histidine-rich region (HRR), and a C-terminal domain. To date, structural information of HRG has largely come from sequence analysis and spectroscopic studies. It is thought that an HRG fragment containing the HRR, released via plasmin-mediated cleavage, acts as a negative regulator of angiogenesis in vivo. However, its release also requires cleavage of a disulphide bond suggesting that its activity is mediated by a redox process. Here, we present a 1.93 Å resolution crystal structure of the N2 domain of serum-purified rabbit HRG. The structure confirms that the N2 domain, which along with the N1 domain, forms an important molecular interaction site on HRG, possesses a cystatin-like fold composed of a 5-stranded antiparallel β-sheet wrapped around a 5-turn α-helix. A native N-linked glycosylation site was identified at Asn184. Moreover, the structure reveals the presence of an S-glutathionyl adduct at Cys185, which has implications for the redox-mediated release of the antiangiogenic cleavage product from HRG.
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205
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Prieto-García A, Castells MC, Hansbro PM, Stevens RL. Mast cell-restricted tetramer-forming tryptases and their beneficial roles in hemostasis and blood coagulation. Immunol Allergy Clin North Am 2014; 34:263-81. [PMID: 24745673 DOI: 10.1016/j.iac.2014.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Tetramer-forming tryptase (hTryptase-β) was recently discovered to have a prominent role in preventing the internal accumulation of life-threatening fibrin deposits and fibrin-platelet clots. The anticoagulant activity of hTryptase-β is an explanation for the presence of hemorrhagic disorders in some patients with anaphylaxis or mastocytosis. The fragments of hFibrinogen formed by the proteolysis of this prominent protein by hTryptase-β could be used as biomarkers in the blood and/or urine for the identification and monitoring of patients with mast cell-dependent disorders. Recombinant hTryptase-β has potential to be used in clinical settings where it is desirable to inhibit blood coagulation.
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Affiliation(s)
- Alicia Prieto-García
- Allergy Service, Hospital Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, Dr Esquerdo 46, Madrid 28007, Spain.
| | - Mariana C Castells
- Division of Rheumatology, Immunology, and Allergy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 1 Jimmy Fund Way, Smith Building, Boston, MA 02115, USA
| | - Philip M Hansbro
- Priority Research Centre for Asthma and Respiratory Disease, Hunter Medical Research Institute and University of Newcastle, 1 Kookaburra Circuit, Newcastle, NSW 2300, Australia
| | - Richard L Stevens
- Division of Rheumatology, Immunology, and Allergy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 1 Jimmy Fund Way, Smith Building, Boston, MA 02115, USA
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206
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Shah S, Khajuria V, Tandon VR, Gillani ZH, Lal M. Comparative evaluation of efficacy, safety and haemostatic parameters of enoxaparin and fondaparinux in unstable coronary artery disease. J Clin Diagn Res 2014; 8:31-4. [PMID: 24596717 DOI: 10.7860/jcdr/2014/6359.3908] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Accepted: 10/19/2013] [Indexed: 01/22/2023]
Abstract
AIM To compare the safety and efficacy of Enoxaparin (EX) and Fondaparinux (FD) in patients with Unstable Coronary Artery Disease (UCAD). MATERIALS AND METHODS A prospective, open label, randomized comparative study was designed to study the comparative efficacy and safety of EX and FD in UCAD patients. Recovery, recurrence, major and minor bleeding and biochemical investigations were evaluated and compared among two arms. RESULTS The baseline demographic characteristics were similar in both groups, with mean age of 56.05 and 56.05 years in EX and FD group respectively. Recovery was equal in two arms. Recurrent MI or angina was seen numerically more in EX group, but it did not statistically vary from that in the FD group. Incidence of haemorrhage was similar in both groups at 9 days, but at 30 days, EX showed a higher incidence (p<0.05). Deaths were prevented in both the treatment arms. Bleeding parameters such as BT, CT and platelet count were not altered in both groups. CONCLUSION FD appeared to be better than EX in efficacy, as was indicated by a numerically more decrease in recurrence of angina or MI. FD regimen group also had better safety profile, as there was no incidence of haemorrhage at 30 days Therefore, we conclude that FD is an attractive option than EX in UCAD patients.
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Affiliation(s)
- Sanjay Shah
- Senior Demonstrator, Department of Pharmacology, Government Medical College , Jammu and Kashmir, India
| | - Vijay Khajuria
- Associate Professor, Department of Pharmacology, Government Medical College , Jammu and Kashmir, India
| | - Vishal R Tandon
- Assistant Professor, Department of Pharmacology, Government Medical College , Jammu and Kashmir, India
| | - Zahid H Gillani
- Professor and Head, Department of Pharmacology, Government Medical College , Jammu and Kashmir, India
| | - Mohan Lal
- Ex-Professor & Head, Department of Cardiology, Government Medical College , Jammu and Kashmir, India
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207
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Abstract
Numerous proteins, including cytokines and chemokines, enzymes and enzyme inhibitors, extracellular matrix proteins, and membrane receptors, bind heparin. Although they are traditionally classified as heparin-binding proteins, under normal physiological conditions these proteins actually interact with the heparan sulfate chains of one or more membrane or extracellular proteoglycans. Thus, they are more appropriately classified as heparan sulfate-binding proteins (HSBPs). This review provides an overview of the various modes of interaction between heparan sulfate and HSBPs, emphasizing biochemical and structural insights that improve our understanding of the many biological functions of heparan sulfate.
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Affiliation(s)
- Ding Xu
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, California 92093; ,
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208
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Nagae M, Yamaguchi Y. Three-dimensional structural aspects of protein-polysaccharide interactions. Int J Mol Sci 2014; 15:3768-83. [PMID: 24595239 PMCID: PMC3975366 DOI: 10.3390/ijms15033768] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 02/17/2014] [Accepted: 02/21/2014] [Indexed: 12/18/2022] Open
Abstract
Linear polysaccharides are typically composed of repeating mono- or disaccharide units and are ubiquitous among living organisms. Polysaccharide diversity arises from chain-length variation, branching, and additional modifications. Structural diversity is associated with various physiological functions, which are often regulated by cognate polysaccharide-binding proteins. Proteins that interact with linear polysaccharides have been identified or developed, such as galectins and polysaccharide-specific antibodies, respectively. Currently, data is accumulating on the three-dimensional structure of polysaccharide-binding proteins. These proteins are classified into two types: exo-type and endo-type. The former group specifically interacts with the terminal units of polysaccharides, whereas the latter with internal units. In this review, we describe the structural aspects of exo-type and endo-type protein-polysaccharide interactions. Further, we discuss the structural basis for affinity and specificity enhancement in the face of inherently weak binding interactions.
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Affiliation(s)
- Masamichi Nagae
- Structural Glycobiology Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| | - Yoshiki Yamaguchi
- Structural Glycobiology Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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209
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Sterner E, Masuko S, Li G, Li L, Green DE, Otto NJ, Xu Y, DeAngelis PL, Liu J, Dordick JS, Linhardt RJ. Fibroblast growth factor-based signaling through synthetic heparan sulfate blocks copolymers studied using high cell density three-dimensional cell printing. J Biol Chem 2014; 289:9754-65. [PMID: 24563485 DOI: 10.1074/jbc.m113.546937] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Four well-defined heparan sulfate (HS) block copolymers containing S-domains (high sulfo group content) placed adjacent to N-domains (low sulfo group content) were chemoenzymatically synthesized and characterized. The domain lengths in these HS block co-polymers were ~40 saccharide units. Microtiter 96-well and three-dimensional cell-based microarray assays utilizing murine immortalized bone marrow (BaF3) cells were developed to evaluate the activity of these HS block co-polymers. Each recombinant BaF3 cell line expresses only a single type of fibroblast growth factor receptor (FGFR) but produces neither HS nor fibroblast growth factors (FGFs). In the presence of different FGFs, BaF3 cell proliferation showed clear differences for the four HS block co-polymers examined. These data were used to examine the two proposed signaling models, the symmetric FGF2-HS2-FGFR2 ternary complex model and the asymmetric FGF2-HS1-FGFR2 ternary complex model. In the symmetric FGF2-HS2-FGFR2 model, two acidic HS chains bind in a basic canyon located on the top face of the FGF2-FGFR2 protein complex. In this model the S-domains at the non-reducing ends of the two HS proteoglycan chains are proposed to interact with the FGF2-FGFR2 protein complex. In contrast, in the asymmetric FGF2-HS1-FGFR2 model, a single HS chain interacts with the FGF2-FGFR2 protein complex through a single S-domain that can be located at any position within an HS chain. Our data comparing a series of synthetically prepared HS block copolymers support a preference for the symmetric FGF2-HS2-FGFR2 ternary complex model.
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Affiliation(s)
- Eric Sterner
- From the Department of Chemical and Biological Engineering
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210
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Quinderé ALG, Santos GRC, Oliveira SNMCG, Glauser BF, Fontes BP, Queiroz INL, Benevides NMB, Pomin VH, Mourão PAS. Is the antithrombotic effect of sulfated galactans independent of serpin? J Thromb Haemost 2014; 12:43-53. [PMID: 24261511 DOI: 10.1111/jth.12448] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 10/31/2013] [Indexed: 01/28/2023]
Abstract
BACKGROUND Sulfated galactans are polysaccharides with heterogeneous structures that frequently show anticoagulant activity. Their anticoagulant mechanisms are complex and distinct from those observed for heparin. Sulfated galactans act through a combination of effects involving serpin-dependent and serpin-independent mechanisms. Interestingly, these polymers can also induce blood coagulation due to activation of factor XII (FXII). OBJECTIVES The structure of a complex sulfated galactan from the red alga Acanthophora muscoides was characterized by solution nuclear magnetic resonance. This polysaccharide and another previously characterized algal sulfated galactan from Botryocladia occidentalis were each used in in vitro and in vivo anticoagulant and antithrombotic assays to understand the possible structural determinants of their functional effects. RESULTS AND CONCLUSIONS The serpin-dependent anticoagulant effects and FXII-related procoagulant effects of the sulfated galactans decreased in parallel with the molecular size. The serpin-independent anticoagulation also correlated with the chemical structure of the sulfated galactans. The sulfated galactan from A. muscoides, which showed mostly serpin-independent anticoagulant activity and reduced activation of FXII, drastically reduced arterial thrombus formation. However, the sulfated galactans produced opposite effects on venous thrombosis; this difference appears to result from the tenuous balance between the various effects on coagulation, including serpin-dependent and serpin-independent anticoagulation and FXIIa-dependent procoagulation. This study of novel sulfated polysaccharides with distinct effects on coagulation and thrombosis helps to establish the minimal structural-function relationship required for the development of antithrombotic drugs.
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Affiliation(s)
- A-L G Quinderé
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, Brazil
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211
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Gooptu B, Dickens JA, Lomas DA. The molecular and cellular pathology of α₁-antitrypsin deficiency. Trends Mol Med 2013; 20:116-27. [PMID: 24374162 DOI: 10.1016/j.molmed.2013.10.007] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 10/28/2013] [Accepted: 10/31/2013] [Indexed: 12/30/2022]
Abstract
Since its discovery 50 years ago, α₁-antitrypsin deficiency has represented a case study in molecular medicine, with careful clinical characterisation guiding genetic, biochemical, biophysical, structural, cellular, and in vivo studies. Here we highlight the milestones in understanding the disease mechanisms and show how they have spurred the development of novel therapeutic strategies. α₁-Antitrypsin deficiency is an archetypal conformational disease. Its pathogenesis demonstrates the interplay between protein folding and quality control mechanisms, with aberrant conformational changes causing liver and lung disease through combined loss- and toxic gain-of-function effects. Moreover, α₁-antitrypsin exemplifies the ability of diverse proteins to self-associate into a range of morphologically distinct polymers, suggesting a mechanism for protein and cell evolution.
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Affiliation(s)
- Bibek Gooptu
- Division of Asthma, Allergy, and Lung Biology, King's College London, 5th Floor, Tower Wing, Guy's Hospital, London, SE1 9RT, UK; Institute of Structural and Molecular Biology/Crystallography, Department of Biological Sciences, Birkbeck College, University of London, Malet Street, London, WC1E 7HX, UK
| | - Jennifer A Dickens
- Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Cambridge, CB2 0XY, UK
| | - David A Lomas
- Institute of Structural and Molecular Biology/Crystallography, Department of Biological Sciences, Birkbeck College, University of London, Malet Street, London, WC1E 7HX, UK; Division of Medicine, University College London, 1st Floor, Maple House, 149, Tottenham Court Road, London, W1T 7NF, UK.
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212
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Thacker BE, Xu D, Lawrence R, Esko JD. Heparan sulfate 3-O-sulfation: a rare modification in search of a function. Matrix Biol 2013; 35:60-72. [PMID: 24361527 DOI: 10.1016/j.matbio.2013.12.001] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 12/03/2013] [Accepted: 12/03/2013] [Indexed: 02/02/2023]
Abstract
Many protein ligands bind to heparan sulfate, which results in their presentation, protection, oligomerization or conformational activation. Binding depends on the pattern of sulfation and arrangement of uronic acid epimers along the chains. Sulfation at the C3 position of glucosamine is a relatively rare, yet biologically significant modification, initially described as a key determinant for binding and activation of antithrombin and later for infection by type I herpes simplex virus. In mammals, a family of seven heparan sulfate 3-O-sulfotransferases installs sulfate groups at this position and constitutes the largest group of sulfotransferases involved in heparan sulfate formation. However, to date very few proteins or biological systems have been described that are influenced by 3-O-sulfation. This review describes our current understanding of the prevalence and structure of 3-O-sulfation sites, expression and substrate specificity of the 3-O-sulfotransferase family and the emerging roles of 3-O-sulfation in biology.
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Affiliation(s)
- Bryan E Thacker
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093-0687, United States; Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92093-0687, United States
| | - Ding Xu
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093-0687, United States
| | - Roger Lawrence
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093-0687, United States
| | - Jeffrey D Esko
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093-0687, United States; Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92093-0687, United States.
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214
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Luxembourg B, Pavlova A, Geisen C, Spannagl M, Bergmann F, Krause M, Alesci S, Seifried E, Lindhoff-Last E. Impact of the type of SERPINC1 mutation and subtype of antithrombin deficiency on the thrombotic phenotype in hereditary antithrombin deficiency. Thromb Haemost 2013; 111:249-57. [PMID: 24196373 DOI: 10.1160/th13-05-0402] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Accepted: 09/27/2013] [Indexed: 11/05/2022]
Abstract
Mutations in the antithrombin (AT) gene can impair the capacity of AT to bind heparin (AT deficiency type IIHBS), its target proteases such as thrombin (type IIRS), or both (type IIPE). Type II AT deficiencies are almost exclusively caused by missense mutations, whereas type I AT deficiency can originate from missense or null mutations. In a retrospective cohort study, we investigated the impact of the type of mutation and type of AT deficiency on the manifestation of thromboembolic events in 377 patients with hereditary AT deficiencies (133 from our own cohort, 244 reported in the literature). Carriers of missense mutations showed a lower risk of venous thromboembolism (VTE) than those of null mutations (adjusted hazard ratio [HR] 0.39, 95% confidence interval [CI] 0.27-0.58, p<0.001), and the risk of VTE was significantly decreased among patients with type IIHBS AT deficiency compared to patients with other types of AT deficiency (HR 0.23, 95%CI 0.13-0.41, p<0.001). The risk of pulmonary embolism complicating deep-vein thrombosis was lower in all type II AT deficiencies compared to type I AT deficiency (relative risk 0.69, 95%CI 0.56-0.84). By contrast, the risk of arterial thromboembolism tended to be higher in carriers of missense mutations than in those with null mutations (HR 6.08-fold, 95%CI 0.74-49.81, p=0.093) and was 5.9-fold increased (95%CI 1.22-28.62, p=0.028) in type IIHBS versus other types of AT deficiency. Our data indicate that the type of inherited AT defect modulates not only the risk of thromboembolism but also the localisation and encourage further studies to unravel this phenomenon.
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Affiliation(s)
- Beate Luxembourg
- Beate Luxembourg, MD, Institute of Transfusion Medicine and Immunohaematology, Department of Molecular Haemostaseology, DRK Blood Donor Service Baden-Württemberg - Hessen, Sandhofstr. 1, 60528 Frankfurt a.M., Germany, Tel.: +49 69 6782 353, Fax: +49 69 6782 346, E-mail:
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215
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Alvarenga PH, Xu X, Oliveira F, Chagas AC, Nascimento CR, Francischetti IMB, Juliano MA, Juliano L, Scharfstein J, Valenzuela JG, Ribeiro JMC, Andersen JF. Novel family of insect salivary inhibitors blocks contact pathway activation by binding to polyphosphate, heparin, and dextran sulfate. Arterioscler Thromb Vasc Biol 2013; 33:2759-70. [PMID: 24092749 DOI: 10.1161/atvbaha.113.302482] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Polyphosphate and heparin are anionic polymers released by activated mast cells and platelets that are known to stimulate the contact pathway of coagulation. These polymers promote both the autoactivation of factor XII and the assembly of complexes containing factor XI, prekallikrein, and high-molecular-weight kininogen. We are searching for salivary proteins from blood-feeding insects that counteract the effect of procoagulant and proinflammatory factors in the host, including elements of the contact pathway. APPROACH AND RESULTS Here, we evaluate the ability of the sand fly salivary proteins, PdSP15a and PdSP15b, to inhibit the contact pathway by disrupting binding of its components to anionic polymers. We attempt to demonstrate binding of the proteins to polyphosphate, heparin, and dextran sulfate. We also evaluate the effect of this binding on contact pathway reactions. We also set out to determine the x-ray crystal structure of PdSP15b and examine the determinants of relevant molecular interactions. Both proteins bind polyphosphate, heparin, and dextran sulfate with high affinity. Through this mechanism they inhibit the autoactivation of factor XII and factor XI, the reciprocal activation of factor XII and prekallikrein, the activation of factor XI by thrombin and factor XIIa, the cleavage of high-molecular-weight kininogen in plasma, and plasma extravasation induced by polyphosphate. The crystal structure of PdSP15b contains an amphipathic helix studded with basic side chains that forms the likely interaction surface. CONCLUSIONS The results of these studies indicate that the binding of anionic polymers by salivary proteins is used by blood feeders as an antihemostatic/anti-inflammatory mechanism.
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Affiliation(s)
- Patricia H Alvarenga
- From the Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health, Rockville, MD (P.H.A., X.X., F.O., A.C.C., I.M.B.F., J.G.V., J.M.C.R., J.F.A.); Laboratório de Bioquímica de Resposta ao Estresse, Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil (P.H.A.); Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil (P.H.A.); Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil (C.R.N., J.S.); and Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil (M.A.J., L.J.)
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216
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Gesslbauer B, Theuer M, Schweiger D, Adage T, Kungl AJ. New targets for glycosaminoglycans and glycosaminoglycans as novel targets. Expert Rev Proteomics 2013; 10:77-95. [PMID: 23414361 DOI: 10.1586/epr.12.75] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Biological functions of a variety of proteins are mediated via their interaction with glycosaminoglycans (GAGs). The structural diversity within the wide GAG landscape provides individual interaction sites for a multitude of proteins involved in several pathophysiological processes. This 'GAG angle' of such proteins as well as their specific GAG ligands give rise to novel therapeutic concepts for drug development. Current glycomic technologies to elucidate the glycan structure-function relationships, methods to investigate the selectivity and specificity of glycan-protein interactions and existing therapeutic approaches to interfere with GAG-protein interactions are discussed.
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Affiliation(s)
- Bernd Gesslbauer
- ProtAffin Biotechnologie AG, Reininghausstrasse 13a, 8020 Graz, Austria
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Maruyama K, Morishita E, Karato M, Kadono T, Sekiya A, Goto Y, Sato T, Nomoto H, Omi W, Tsuzura S, Imai H, Asakura H, Ohtake S, Nakao S. Antithrombin deficiency in three Japanese families: one novel and two reported point mutations in the antithrombin gene. Thromb Res 2013; 132:e118-23. [PMID: 23809926 DOI: 10.1016/j.thromres.2013.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 05/25/2013] [Accepted: 06/02/2013] [Indexed: 11/18/2022]
Abstract
INTRODUCTION Inherited antithrombin (AT) deficiency is associated with a predisposition to familial venous thromboembolic disease. We analyzed the AT gene in three unrelated patients with an AT deficiency who developed thrombosis. MATERIALS AND METHODS We analyzed the SERPINC1 gene in three patients. Additionally, we expressed the three mutants in the COS-1 cells and compared their secretion rates and levels of AT activity with those of the wild-type (WT). RESULTS We identified three distinct heterozygous mutations of c.2534C>T: p.56Arginine → Cysteine (R56C), c.13398C>A: p.459Alanine → Aspartic acid (A459D) and c.2703C>G: p.112 Proline → Arginine (P112R). In the in vitro expression experiments, the AT antigen levels in the conditioned media (CM) of the R56C mutant were nearly equal to those of WT. In contrast, the AT antigen levels in the CM of the A459D and P112R mutants were significantly decreased. The AT activity of R56C was decreased in association with a shorter incubation time in a FXa inhibition assay and a thrombin inhibition-based activity test. However, the AT activity of R56C was comparable to that of WT when the incubation time was increased. CONCLUSIONS We concluded that the R56C mutant is responsible for type II HBS deficiency. We considered that the A459D and P112R mutants can be classified as belonging to the type I AT deficiency.
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Affiliation(s)
- Keiko Maruyama
- Department of Clinical Laboratory Science, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
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Wang J, Wang Y, Wang J, Gao J, Tong C, Manithody C, Li J, Rezaie AR. Antithrombin is protective against myocardial ischemia and reperfusion injury. J Thromb Haemost 2013; 11:1020-8. [PMID: 23582062 PMCID: PMC3702629 DOI: 10.1111/jth.12243] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Indexed: 11/30/2022]
Abstract
BACKGROUND Antithrombin (AT) is a plasma serpin inhibitor that regulates the proteolytic activity of procoagulant proteases of the clotting cascade. In addition to its anticoagulant activity, AT also possesses potent anti-inflammatory properties. OBJECTIVES The objective of this study was to investigate the anti-inflammatory activity of wild-type AT (AT-WT) and a reactive centre loop mutant of AT (AT-RCL) which is not capable of inhibiting thrombin. METHODS The cardioprotective activities of AT-WT and AT-RCL were monitored in a mouse model of ischemia/reperfusion (I/R) injury in which the left anterior descending coronary artery was occluded and then released. RESULTS We demonstrate that AT markedly reduces myocardial infarct size by a mechanism that is independent of its anticoagulant activity. Thus, AT-RCL attenuated myocardial infarct size to the same extent as AT-WT in this acute injury model. Further studies revealed that AT binds to vascular heparan sulfate proteoglycans via its heparin-binding domain to exert its protective activity as evidenced by the therapeutic AT-binding pentasaccharide (fondaparinux) abrogating the cardioprotective activity of AT and a heparin-site mutant of AT exhibiting no cardioprotective property. We further demonstrate that AT up-regulates the production of prostacyclin in myocardial tissues and inhibits expression of pro-inflammatory cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6 in vivo by attenuating ischemia/reperfusion-induced JNK and NF-κB signaling pathways. CONCLUSIONS The present results suggest that both AT and the non-anticoagulant AT-RCL, through their anti-inflammatory signaling effects, elicit potent cardioprotective responses. Thus, AT may have therapeutic potential for treating cardiac I/R injury.
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Affiliation(s)
- Jingying Wang
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo-SUNY, Buffalo, NY
| | - Yanqing Wang
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo-SUNY, Buffalo, NY
| | - Jinli Wang
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo-SUNY, Buffalo, NY
| | - Junjie Gao
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo-SUNY, Buffalo, NY
| | - Chao Tong
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo-SUNY, Buffalo, NY
| | - Chandrashekhara Manithody
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, MO
| | - Ji Li
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo-SUNY, Buffalo, NY
| | - Alireza R. Rezaie
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, MO
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An unusual antithrombin-binding heparin octasaccharide with an additional 3-O-sulfated glucosamine in the active pentasaccharide sequence. Biochem J 2013; 449:343-51. [PMID: 23083208 DOI: 10.1042/bj20121309] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The 3-O-sulfation of N-sulfated glucosamine is the last event in the biosynthesis of heparin/heparan sulfate, giving rise to the antithrombin-binding pentasaccharide sequence AGA*IA, which is largely associated with the antithrombotic activity of these molecules. The aim of the present study was the structural and biochemical characterization of a previously unreported AGA*IA*-containing octasaccharide isolated from the very-low-molecular-mass heparin semuloparin, in which both glucosamine residues of the pentasaccharide moiety located at the non-reducing end bear 3-O-sulfate groups. Two-dimensional and STD (saturation transfer difference) NMR experiments clearly confirmed its structure and identified its ligand epitope binding to antithrombin. The molecular conformation of the octasaccharide-antithrombin complex has been determined by NMR experiments and docking/energy minimization. The presence of the second 3-O-sulfated glucosamine in the octasaccharide induced more than one order of magnitude increase in affinity to antithrombin compared to the pentasaccharide AGA*IA.
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220
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Gomes FM, Carvalho DB, Machado EA, Miranda K. Ultrastructural and functional analysis of secretory goblet cells in the midgut of the lepidopteran Anticarsia gemmatalis. Cell Tissue Res 2013; 352:313-26. [PMID: 23397424 DOI: 10.1007/s00441-013-1563-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 01/03/2013] [Indexed: 11/25/2022]
Abstract
Defoliation caused by Anticarsia gemmatalis larvae affects the commercial production of the soybean. Although regulation of the digestion of soybean components has become part of the suggested strategy to overcome problems caused by Anticarsia larvae, few studies have focused on the morphological and cellular aspects of Anticarsia intestinal tissue. We have therefore further analyzed the morphology and ultrastructure of the midgut of 5th instar larvae of A. gemmatalis. Dissected midgut was subjected to chemical or cryo-fixation and then to several descriptive and analytical techniques associated with both light and electron microscopy in order to correlate anatomical and physiological aspects of this organ. Histological analysis revealed typical anatomy composed of a cell layer limited by a peritrophic membrane. The identified lepidoptera-specific goblet cells were shown to contain several mitochondria inside microvilli of the goblet cell cavity and a vacuolar H(+)-ATPase possibly coupled to a K(+)-pumping system. Columnar cells were present and exhibited microvilli dispersed along the apical region that also presented secretory characteristics. We additionally found evidence for the secretion of polyphosphate (PolyP) into the midgut, a result corroborating previous reports suggesting an excretion route from the goblet cell cavity toward the luminal space. Thus, our results suggest that the Anticarsia midgut not only possesses several typical lepidopteran features but also presents some unique aspects such as the presence of a tubular network and PolyP-containing apocrine secretions, plus an apparent route for the release of cellular debris by the goblet cells.
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Affiliation(s)
- F M Gomes
- Instituto de Biofísica Carlos Chagas Filho and Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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221
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Gulley MM, Zhang X, Michel K. The roles of serpins in mosquito immunology and physiology. JOURNAL OF INSECT PHYSIOLOGY 2013; 59:138-47. [PMID: 22960307 PMCID: PMC3560325 DOI: 10.1016/j.jinsphys.2012.08.015] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/24/2012] [Accepted: 08/28/2012] [Indexed: 05/10/2023]
Abstract
In vector-borne diseases, the complex interplay between pathogen and its vector's immune system determines the outcome of infection and therefore disease transmission. Serpins have been shown in many animals to be key regulators of innate immune reactions. Their control over regulatory proteolytic cascades ultimately decides whether the recognition of a pathogen will lead to an appropriate immune response. In mosquitoes, serpins (SRPNs) regulate the activation of prophenoloxidase and thus melanization, contribute to malaria parasite lysis, and likely Toll pathway activation. Additionally, in culicine mosquitoes, SRPNs are able to regulate hemostasis in the vertebrate host, suggesting a crucial role during bloodfeeding. This review summarizes the annotation, transcriptional regulation, and current knowledge of SRPN function in the three mosquito species for which the complete genome sequence is available. Additionally, we give a brief overview of how SRPNs may be used to prevent transmission of vector-borne diseases.
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Affiliation(s)
| | | | - Kristin Michel
- Corresponding author: tel.: +1 (785) 532-0161, fax: +1 (785) 532-6653;
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222
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Lima MA, Viskov C, Herman F, Gray AL, de Farias EHC, Cavalheiro RP, Sassaki GL, Hoppensteadt D, Fareed J, Nader HB. Ultra-low-molecular-weight heparins: precise structural features impacting specific anticoagulant activities. Thromb Haemost 2013; 109:471-8. [PMID: 23329070 DOI: 10.1160/th12-11-0795] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 12/07/2012] [Indexed: 11/05/2022]
Abstract
Ultra-low-molecular-weight heparins (ULMWHs) with better efficacy and safety ratios are under development; however, there are few structural data available. The main structural features and molecular weight of ULMWHs were studied and compared to enoxaparin. Their monosaccharide composition and average molecular weights were determined and preparations studied by nuclear magnetic resonance spectroscopy, scanning ultraviolet spectroscopy, circular dichroism and gel permeation chromatography. In general, ULMWHs presented higher 3-O-sulphated glucosamine and unsaturated uronic acid residues, the latter being comparable with their higher degree of depolymerisation. The analysis showed that ULMWHs are structurally related to LMWHs; however, their monosaccharide/oligosaccharide compositions and average molecular weights differed considerably explaining their different anticoagulant activities. The results relate structural features to activity, assisting the development of new and improved therapeutic agents, based on depolymerised heparin, for the prophylaxis and treatment of thrombotic disorders.
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Affiliation(s)
- Marcelo A Lima
- Disciplina de Biologia Molecular, Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, 04044-020, Brazil
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223
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Remko M, Van Duijnen PT, Broer R. Effect of metal ions (Li+, Na+, K+, Mg2+ and Ca2+) and water on the conformational changes of glycosidic bonds in heparin oligosaccharides. RSC Adv 2013. [DOI: 10.1039/c3ra40566d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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224
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Remko M, Duijnen PTV, Broer R. Structure and stability of complexes of charged structural units of heparin with arginine and lysine. RSC Adv 2013. [DOI: 10.1039/c2ra22062h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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225
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Gardill BR, Vogl MR, Lin HY, Hammond GL, Muller YA. Corticosteroid-binding globulin: structure-function implications from species differences. PLoS One 2012; 7:e52759. [PMID: 23300763 PMCID: PMC3530532 DOI: 10.1371/journal.pone.0052759] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 11/20/2012] [Indexed: 11/18/2022] Open
Abstract
Corticosteroid-binding globulin (CBG) transports glucocorticoids and progesterone in the blood and thereby modulates the tissue availability of these hormones. As a member of the serine protease inhibitor (SERPIN) family, CBG displays a reactive center loop (RCL) that is targeted by proteinases. Cleavage of the RCL is thought to trigger a SERPIN-typical stressed-to-relaxed (S-to-R) transition that leads to marked structural rearrangements and a reduced steroid-binding affinity. To characterize structure-function relationships in CBG we studied various conformational states of E. coli-produced rat and human CBG. In the 2.5 Å crystal structure of human CBG in complex with progesterone, the RCL is cleaved at a novel site that differs from the known human neutrophil elastase recognition site. Although the cleaved RCL segment is five residues longer than anticipated, it becomes an integral part of β-sheet A as a result of the S-to-R transition. The atomic interactions observed between progesterone and CBG explain the lower affinity of progesterone in comparison to corticosteroids. Surprisingly, CD measurements in combination with thermal unfolding experiments show that rat CBG fails to undergo an S-to-R transition upon proteolytic cleavage of the RCL hinting that the S-to-R transition observed in human CBG is not a prerequisite for CBG function in rat. This observation cautions against drawing general conclusions about molecular mechanisms by comparing and merging structural data from different species.
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Affiliation(s)
- Bernd R. Gardill
- Department of Biology, Lehrstuhl für Biotechnik, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Michael R. Vogl
- Department of Biology, Lehrstuhl für Biotechnik, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Hai-Yan Lin
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Geoffrey L. Hammond
- Department of Obstetrics and Gynecology, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Yves A. Muller
- Department of Biology, Lehrstuhl für Biotechnik, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
- * E-mail:
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226
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Mosier PD, Krishnasamy C, Kellogg GE, Desai UR. On the specificity of heparin/heparan sulfate binding to proteins. Anion-binding sites on antithrombin and thrombin are fundamentally different. PLoS One 2012; 7:e48632. [PMID: 23152789 PMCID: PMC3495972 DOI: 10.1371/journal.pone.0048632] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Accepted: 10/03/2012] [Indexed: 11/25/2022] Open
Abstract
Background The antithrombin–heparin/heparan sulfate (H/HS) and thrombin–H/HS interactions are recognized as prototypic specific and non-specific glycosaminoglycan (GAG)–protein interactions, respectively. The fundamental structural basis for the origin of specificity, or lack thereof, in these interactions remains unclear. The availability of multiple co-crystal structures facilitates a structural analysis that challenges the long-held belief that the GAG binding sites in antithrombin and thrombin are essentially similar with high solvent exposure and shallow surface characteristics. Methodology Analyses of solvent accessibility and exposed surface areas, gyrational mobility, symmetry, cavity shape/size, conserved water molecules and crystallographic parameters were performed for 12 X-ray structures, which include 12 thrombin and 16 antithrombin chains. Novel calculations are described for gyrational mobility and prediction of water loci and conservation. Results The solvent accessibilities and gyrational mobilities of arginines and lysines in the binding sites of the two proteins reveal sharp contrasts. The distribution of positive charges shows considerable asymmetry in antithrombin, but substantial symmetry for thrombin. Cavity analyses suggest the presence of a reasonably sized bifurcated cavity in antithrombin that facilitates a firm ‘hand-shake’ with H/HS, but with thrombin, a weaker ‘high-five’. Tightly bound water molecules were predicted to be localized in the pentasaccharide binding pocket of antithrombin, but absent in thrombin. Together, these differences in the binding sites explain the major H/HS recognition characteristics of the two prototypic proteins, thus affording an explanation of the specificity of binding. This provides a foundation for understanding specificity of interaction at an atomic level, which will greatly aid the design of natural or synthetic H/HS sequences that target proteins in a specific manner.
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Affiliation(s)
| | | | | | - Umesh R. Desai
- Department of Medicinal Chemistry and Institute of Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia, United States of America
- * E-mail:
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227
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An C, Hiromasa Y, Zhang X, Lovell S, Zolkiewski M, Tomich JM, Michel K. Biochemical characterization of Anopheles gambiae SRPN6, a malaria parasite invasion marker in mosquitoes. PLoS One 2012; 7:e48689. [PMID: 23152794 PMCID: PMC3494705 DOI: 10.1371/journal.pone.0048689] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 10/01/2012] [Indexed: 01/14/2023] Open
Abstract
Serine proteinase inhibitors of the serpin family are well known as negative regulators of hemostasis, thrombolysis and innate immune responses. Additionally, non-inhibitory serpins serve functions as chaperones, hormone transporters, or anti-angiogenic factors. In the African malaria mosquito, Anopheles gambiae s.s., at least three serpins (SRPNs) are implicated in the innate immune response against malaria parasites. Based on reverse genetic and cell biological analyses, AgSRPN6 limits parasite numbers and transmission and has been postulated to control melanization and complement function in mosquitoes. This study aimed to characterize AgSRPN6 biophysically and determine its biochemical mode of action. The structure model of AgSRPN6, as predicted by I-Tasser showed the protein in the native serpin fold, with three central β-sheets, nine surrounding α-helices, and a protruding reactive center loop. This structure is in agreement with biophysical and functional data obtained from recombinant (r) AgSRPN6, produced in Escherichia coli. The physical properties of purified rAgSRPN6 were investigated by means of analytical ultracentrifugation, circular dichroism, and differential scanning calorimetry tools. The recombinant protein exists predominantly as a monomer in solution, is composed of a mixture of α-helices and β-sheets, and has a mid-point unfolding temperature of 56°C. Recombinant AgSRPN6 strongly inhibited porcine pancreatic kallikrein and to a lesser extent bovine pancreatic trypsin in vitro. Furthermore, rAgSRPN6 formed inhibitory, SDS-stable, higher molecular weight complexes with prophenoloxidase-activating proteinase (PAP)1, PAP3, and Hemolymph protein (HP)6, which are required for melanization in the lepidopteran model organism, Manduca sexta. Taken together, our results strongly suggest that AgSRPN6 takes on a native serpin fold and is an inhibitor of trypsin-like serine proteinases.
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Affiliation(s)
- Chunju An
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
- Department of Entomology, China Agricultural University, Beijing, China
| | - Yasuaki Hiromasa
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, United States of America
| | - Xin Zhang
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - Scott Lovell
- Protein Structure Laboratory, University of Kansas, Lawrence, Kansas, United States of America
| | - Michal Zolkiewski
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, United States of America
| | - John M. Tomich
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, United States of America
| | - Kristin Michel
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
- * E-mail:
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228
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Stevic I, Chan HHW, Berry LR, Chander A, Chan AKC. Inhibition of the prothrombinase complex on red blood cells by heparin and covalent antithrombin-heparin complex. J Biochem 2012; 153:103-10. [PMID: 23100269 DOI: 10.1093/jb/mvs129] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The role of red blood cells (RBCs) in coagulation is not well understood. Overt exposure of phosphatidylserine on surfaces of RBCs provide docking sites for formation of the prothrombinase complex, which further aids in amplification of coagulation leading to subsequent thrombosis. No studies to date have evaluated heparin inhibition of the RBC-prothrombinase system. Therefore, this study examines the ability of heparin and a covalent antithrombin-heparin complex (ATH) to inhibit the RBC-prothrombinase system. Discontinuous inhibition assays were performed to obtain k₂ values for inhibition of free or prothrombinase-bound Xa by antithrombin and unfractionated heparin (AT + UFH) versus ATH. In addition, components of the complex (prothrombin, RBCs or Va) were excluded prior to reaction with inhibitors to investigate potential mechanisms involved. Inhibition of thrombin generation, fibrinogen conversion and plasma clotting by the RBC-prothrombinase system was also examined. Protection of Xa was observed for AT + UFH and not for ATH reactions. Inhibition rates for ATH were significantly faster when compared with AT + UFH results. The greatest impact on Xa inhibition was observed from factor Va omission for both inhibitors. ATH inhibited thrombin generation, fibrinogen conversion and plasma clotting better compared with AT + UFH. This study determined potential control of coagulation contributed by RBCs. Moreover, greater control of coagulation is achieved by covalently linking heparin to AT.
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Affiliation(s)
- Ivan Stevic
- Thrombosis and Atherosclerosis Research Institute (TaARI), DBCVSRI, Hamilton General Hospital, 237 Barton Street East, Hamilton, ON, L8L 2X2, Canada
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Walenga JM, Jeske WP, Hoppensteadt D, Cunanan J, Khan H, Escalante V, Fareed J, Bakhos M. Comparative studies on branded enoxaparin and a US generic version of enoxaparin. Clin Appl Thromb Hemost 2012; 19:261-7. [PMID: 23091283 DOI: 10.1177/1076029612463427] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Enoxaparin, a complex, biologically derived low-molecular-weight heparin, is approved for a range of clinical indications. This study was carried out to compare the potency profile and pharmacodynamic responses of branded enoxaparin (Lovenox; Sanofi, US) with a generic enoxaparin (enoxaparin sodium injection, USP). Five batches of each product were tested. Although the average molecular weight, anti-factor Xa, and anti-factor IIa potencies were similar for the two products, differences were observed in the in vitro thrombin generation and kinetics of clot formation (P = .01) and in the ex vivo pharmacodynamics regarding thrombin generation inhibition (P = .029), tissue factor pathway inhibitor release (P = .006), and inhibition of the active form of thrombin-activated fibrinolysis inhibitor (P = .023). These findings suggest that simple analytical characterization can establish good quality control in manufacturing, but they may not assure similarity in biological performance between the branded and the generic enoxaparin.
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Affiliation(s)
- Jeanine M Walenga
- Department of Thoracic & Cardiovascular Surgery, Loyola University Chicago, Maywood, IL 60153, USA.
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Lázár L, Mező E, Herczeg M, Lipták A, Antus S, Borbás A. Synthesis of the non-reducing end trisaccharide of the antithrombin-binding domain of heparin and its bioisosteric sulfonic acid analogues. Tetrahedron 2012. [DOI: 10.1016/j.tet.2012.06.081] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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231
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Chemoenzymatic synthesis of the next generation of ultralow MW heparin therapeutics. Future Med Chem 2012; 4:289-96. [PMID: 22393937 DOI: 10.4155/fmc.11.185] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Heparin, a sulfated glycosaminoglycan, is a widely used injectable anticoagulant. This polysaccharide is a natural product extracted from porcine intestinal tissue. A specific pentasaccharide sequence is responsible for heparin's high affinity towards anti-thrombin III, which undergoes a conformational change and, as a result, inhibits the blood coagulation Factor Xa, a critical serine protease at the convergence on the intrinsic and extrinsic activation pathway of the coagulation cascade. Due to its structural complexity and heterogeneity, the synthesis of the anti-thrombin III-binding sequence of heparin has been limited to a few approaches. The heparin contamination crisis in 2007 has motivated the development of alternative methods for the efficient preparation of safe heparin products. In this article, we discuss the current methods and recent advances in heparin and low MW heparin syntheses and the recent successful chemoenzymatic preparation of ultralow MW heparins.
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232
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Structure of an engineered β-lactamase maltose binding protein fusion protein: insights into heterotropic allosteric regulation. PLoS One 2012; 7:e39168. [PMID: 22720063 PMCID: PMC3375305 DOI: 10.1371/journal.pone.0039168] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 05/16/2012] [Indexed: 11/21/2022] Open
Abstract
Engineering novel allostery into existing proteins is a challenging endeavor to obtain novel sensors, therapeutic proteins, or modulate metabolic and cellular processes. The RG13 protein achieves such allostery by inserting a circularly permuted TEM-1 β-lactamase gene into the maltose binding protein (MBP). RG13 is positively regulated by maltose yet is, serendipitously, inhibited by Zn2+ at low µM concentration. To probe the structure and allostery of RG13, we crystallized RG13 in the presence of mM Zn2+ concentration and determined its structure. The structure reveals that the MBP and TEM-1 domains are in close proximity connected via two linkers and a zinc ion bridging both domains. By bridging both TEM-1 and MBP, Zn2+ acts to “twist tie” the linkers thereby partially dislodging a linker between the two domains from its original catalytically productive position in TEM-1. This linker 1 contains residues normally part of the TEM-1 active site including the critical β3 and β4 strands important for activity. Mutagenesis of residues comprising the crystallographically observed Zn2+ site only slightly affected Zn2+ inhibition 2- to 4-fold. Combined with previous mutagenesis results we therefore hypothesize the presence of two or more inter-domain mutually exclusive inhibitory Zn2+ sites. Mutagenesis and molecular modeling of an intact TEM-1 domain near MBP within the RG13 framework indicated a close surface proximity of the two domains with maltose switching being critically dependent on MBP linker anchoring residues and linker length. Structural analysis indicated that the linker attachment sites on MBP are at a site that, upon maltose binding, harbors both the largest local Cα distance changes and displays surface curvature changes, from concave to relatively flat becoming thus less sterically intrusive. Maltose activation and zinc inhibition of RG13 are hypothesized to have opposite effects on productive relaxation of the TEM-1 β3 linker region via steric and/or linker juxtapositioning mechanisms.
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Granzin J, Huang Y, Topbas C, Huang W, Wu Z, Misra S, Hazen SL, Blanton RE, Lee X, Weiergräber OH. Three-dimensional structure of a schistosome serpin revealing an unusual configuration of the helical subdomain. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:686-94. [PMID: 22683791 PMCID: PMC3370883 DOI: 10.1107/s0907444912008372] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 02/24/2012] [Indexed: 11/10/2022]
Abstract
Parasitic organisms are constantly challenged by the defence mechanisms of their respective hosts, which often depend on serine protease activities. Consequently, protease inhibitors such as those belonging to the serpin superfamily have emerged as protective elements that support the survival of the parasites. This report describes the crystal structure of ShSPI, a serpin from the trematode Schistosoma haematobium. The protein is exposed on the surface of invading cercaria as well as of adult worms, suggesting its involvement in the parasite-host interaction. While generally conforming to the well established serpin fold, the structure reveals several distinctive features, mostly concerning the helical subdomain of the protein. It is proposed that these peculiarities are related to the unique biological properties of a small serpin subfamily which is conserved among pathogenic schistosomes.
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Affiliation(s)
- Joachim Granzin
- Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Ying Huang
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Celalettin Topbas
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Wenying Huang
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Zhiping Wu
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Saurav Misra
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Stanley L. Hazen
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Ronald E. Blanton
- Department of Infectious Diseases, Case Western Reserve University, Cleveland, OH 44190, USA
| | - Xavier Lee
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Oliver H. Weiergräber
- Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany
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234
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Abstract
Proteoglycans (PGs) are among the most structurally complex biomacromolecules in nature. They are present in all animal cells and frequently exert their critical biological functions through interactions with protein ligands and receptors. PGs are comprised of a core protein to which one or multiple, heterogeneous, and polydisperse glycosaminoglycan (GAG) chains are attached. Proteins, including the protein core of PGs, are now routinely sequenced either directly using proteomics or indirectly using molecular biology through their encoding DNA. The sequencing of the GAG component of PGs poses a considerably more difficult challenge because of the relatively underdeveloped state of glycomics and because the control of their biosynthesis in the endoplasmic reticulum and the Golgi is poorly understood and not believed to be template driven. Recently, the GAG chain of the simplest PG has been suggested to have a defined sequence based on its top-down Fourier transform mass spectral sequencing. This review examines the advances made over the past decade in the sequencing of GAG chains and the challenges the field face in sequencing complex PGs having critical biological functions in developmental biology and pathogenesis.
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Affiliation(s)
- Lingyun Li
- Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, 12180, USA; Fax: +1 518-276-3405; Tel: +1 518-276-3404
| | - Mellisa Ly
- Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, 12180, USA; Fax: +1 518-276-3405; Tel: +1 518-276-3404
| | - Robert J. Linhardt
- Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, 12180, USA; Fax: +1 518-276-3405; Tel: +1 518-276-3404
- Department of Biology, Chemical and Biological Engineering and Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, 12180, USA
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235
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Sask KN, Berry LR, Chan AKC, Brash JL. Polyurethane modified with an antithrombin-heparin complex via polyethylene oxide linker/spacers: Influence of PEO molecular weight and PEO-ATH bond on catalytic and direct anticoagulant functions. J Biomed Mater Res A 2012; 100:2821-8. [DOI: 10.1002/jbm.a.34218] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 03/28/2012] [Accepted: 04/03/2012] [Indexed: 11/11/2022]
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236
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Crystal structures of protease nexin-1 in complex with heparin and thrombin suggest a 2-step recognition mechanism. Blood 2012; 120:459-67. [PMID: 22618708 DOI: 10.1182/blood-2012-03-415869] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protease nexin-1 (PN1) is a specific and extremely efficient inhibitor of thrombin. However, unlike other thrombin inhibitors belonging to the serpin family, PN1 is not synthesized in the liver and does not circulate in the blood. Rather, PN1 is expressed by multiple cell types, including macrophages, smooth muscle cells, and platelets, and it is on the surface of these cells, bound to glycosaminoglycans, that PN1 inhibits the signaling functions of thrombin. PN1 sets the threshold for thrombin-induced platelet activation and has been implicated in atherosclerosis. However, in spite of the emerging importance of PN1 in thrombosis and atherosclerosis, little is know about how it associates to cells and how it inhibits thrombin at rates that surpass the diffusion limit. To address these issues, we determined the crystal structures of PN1 in complex with heparin, and in complex with catalytically inert thrombin. The crystal structures suggest a unique 2-step mechanism of thrombin recognition involving rapid electrostatics-driven association to form an initial glycosaminoglycan-bridged complex, followed by a large conformational rearrangement to form the productive Michaelis complex.
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237
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Langeslay DJ, Young RP, Beni S, Beecher CN, Mueller LJ, Larive CK. Sulfamate proton solvent exchange in heparin oligosaccharides: evidence for a persistent hydrogen bond in the antithrombin-binding pentasaccharide Arixtra. Glycobiology 2012; 22:1173-82. [PMID: 22593556 DOI: 10.1093/glycob/cws085] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sulfamate groups (NHSO(3)(-)) are important structural elements in the glycosaminoglycans (GAGs) heparin and heparan sulfate (HS). In this work, proton nuclear magnetic resonance (NMR) line-shape analysis is used to explore the solvent exchange properties of the sulfamate NH groups within heparin-related mono-, di-, tetra- and pentasaccharides as a function of pH and temperature. The results of these experiments identified a persistent hydrogen bond within the Arixtra (fondaparinux sodium) pentasaccharide between the internal glucosamine sulfamate NH and the adjacent 3-O-sulfo group. This discovery provides new insights into the solution structure of the Arixtra pentasaccharide and suggests that 3-O-sulfation of the heparin N-sulfoglucosamine (GlcNS) residues pre-organize the secondary structure in a way that facilitates binding to antithrombin-III. NMR studies of the GlcNS NH groups can provide important information about heparin structure complementary to that available from NMR spectral analysis of the carbon-bound protons.
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Affiliation(s)
- Derek J Langeslay
- Department of Chemistry, University of California-Riverside, Riverside, CA 92521, USA
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238
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Stevic I, Berry LR, Chan AKC. Mechanism of inhibition of the prothrombinase complex by a covalent antithrombin-heparin complex. J Biochem 2012; 152:139-48. [DOI: 10.1093/jb/mvs039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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239
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Rashid Q, Singh P, Abid M, Jairajpuri MA. Limitations of conventional anticoagulant therapy and the promises of non-heparin based conformational activators of antithrombin. J Thromb Thrombolysis 2012; 34:251-9. [DOI: 10.1007/s11239-012-0712-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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240
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Abstract
Essentially the same steps are required to solve the crystal structure of a serpin as for any other protein: produce and purify protein, grow crystals, collect diffraction data, find estimates of the phase angles, and then refine and validate the structure. For the phasing step, experimental phasing methods involving heavy atom soaks were required for the first few structures, but with the large number of serpin structures now available, molecular replacement has become the method of choice. Two things are special about serpins. First, because of the central role of conformational change in serpin mechanism, it is advisable to consider a variety of molecular replacement models in different conformations and then to allow for rigid-body motions in the initial refinement steps. Second, probably owing to the flexibility of serpins, the average serpin crystal is significantly less well ordered than the average crystal of another protein, which increases the difficulty of solving and refining their structures.
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241
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Young LK, Birch NP, Browett PJ, Coughlin PB, Horvath AJ, Van de Water NS, Ockelford PA, Harper PL. Two missense mutations identified in venous thrombosis patients impair the inhibitory function of the protein Z dependent protease inhibitor. Thromb Haemost 2012; 107:854-63. [PMID: 22399118 DOI: 10.1160/th11-10-0708] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 01/10/2012] [Indexed: 11/05/2022]
Abstract
Protein Z-dependent protease inhibitor (ZPI) is a plasma inhibitor of factor (F)Xa and FXIa. In an earlier study, five mutations were identified within the ZPI gene of venous thrombosis patients and healthy controls. Two of these were nonsense mutations and three were missense mutations in important regions of the protein. Here we report that two of these latter three mutations, F145L and Q384R, impair the inhibitory function of ZPI in vitro. Recombinant wild-type and mutant proteins were prepared; stability in response to thermal challenge was similar. Inhibition of FXa in the presence of the cofactor protein Z was reduced 68-fold by the Q384R mutant; inhibition of FXIa by the F145L mutant was reduced two- to three-fold compared to the wild-type ZPI. An analysis of all five ZPI mutations was undertaken in a cohort of venous thrombosis patients (n=550) compared to healthy controls (n=600). Overall, there was a modest increase in incidence of these mutations in the thrombosis group (odds ratio 2.0, 1.05-3.7, p=0.044). However, in contrast to W324X (nonsense mutation), the Q384R missense mutation and R88X nonsense mutation were evenly distributed in patients and controls; F145L was rare. The final mutation (S143Y) was also rare and did not significantly alter ZPI function in laboratory studies. The F145L and particularly the Q384R mutation impaired the function of the coagulation inhibitor ZPI; however, there was no convincing association between these mutations and venous thrombosis risk. The functional role for ZPI in vivo has yet to be clarified.
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Affiliation(s)
- Laura K Young
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
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242
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Pomin VH, Park Y, Huang R, Heiss C, Sharp JS, Azadi P, Prestegard JH. Exploiting enzyme specificities in digestions of chondroitin sulfates A and C: production of well-defined hexasaccharides. Glycobiology 2012; 22:826-38. [PMID: 22345629 DOI: 10.1093/glycob/cws055] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Interactions between proteins and glycosaminoglycans (GAGs) of the extracellular matrix are important to the regulation of cellular processes including growth, differentiation and migration. Understanding these processes can benefit greatly from the study of protein-GAG interactions using GAG oligosaccharides of well-defined structure. Materials for such studies have, however, been difficult to obtain because of challenges in synthetic approaches and the extreme structural heterogeneity in GAG polymers. Here, it is demonstrated that diversity in structures of oligosaccharides derived by limited enzymatic digestion of materials from natural sources can be greatly curtailed by a proper selection of combinations of source materials and digestive enzymes, a process aided by an improved understanding of the specificities of certain commercial preparations of hydrolases and lyases. Separation of well-defined oligosaccharides can then be accomplished by size-exclusion chromatography followed by strong anion-exchange chromatography. We focus here on two types of chondroitin sulfate (CS) as starting material (CS-A, and CS-C) and the use of three digestive enzymes with varying specificities (testicular hyaluronidase and bacterial chondroitinases ABC and C). Analysis using nuclear magnetic resonance and mass spectrometry focuses on isolated CS disaccharides and hexasaccharides. In all, 15 CS hexasaccharides have been isolated and characterized. These serve as useful contributions to growing libraries of well-defined GAG oligosaccharides that can be used in further biophysical assays.
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Affiliation(s)
- Vitor H Pomin
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
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243
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Guerrini M, Bisio A. Low-molecular-weight heparins: differential characterization/physical characterization. Handb Exp Pharmacol 2012:127-57. [PMID: 22566224 DOI: 10.1007/978-3-642-23056-1_7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Low-molecular-weight heparins (LMWHs), derived from unfractionated heparin (UFH) through different depolymerization processes, have advantages with respect to the parent heparin in terms of pharmacokinetics, convenience of administration, and reduced side effects. Each LMWH can be considered as an independent drug with its own activity profile, placing significance on their biophysical characterization, which will also enable a better understanding of their structure-function relationship. Several chemical and physical methods, some involving sample modification, are now available and are reviewed.
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Affiliation(s)
- Marco Guerrini
- Istituto di Ricerche Chimiche e Biochimiche G. Ronzoni, Milan, Italy.
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244
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Abstract
The molecular basis for the anticoagulant action of heparin lies in its ability to bind to and enhance the inhibitory activity of the plasma protein antithrombin against several serine proteases of the coagulation system, most importantly factors IIa (thrombin), Xa and IXa. Two major mechanisms underlie heparin's potentiation of antithrombin. The conformational changes induced by heparin binding cause both expulsion of the reactive loop and exposure of exosites of the surface of antithrombin, which bind directly to the enzyme target; and a template mechanism exists in which both inhibitor and enzyme bind to the same heparin molecule. The relative importance of these two modes of action varies between enzymes. In addition, heparin can act through other serine protease inhibitors such as heparin co-factor II, protein C inhibitor and tissue factor plasminogen inhibitor. The antithrombotic action of heparin in vivo, though dominated by anticoagulant mechanisms, is more complex, and interactions with other plasma proteins and cells play significant roles in the living vasculature.
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Affiliation(s)
- Elaine Gray
- National Institute for Biological Standards and Control, Potter's Bar, Hertfordshire, UK.
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245
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Gu X, Zhang G, Zhang D. A new ratiometric fluorescence detection of heparin based on the combination of the aggregation-induced fluorescence quenching and enhancement phenomena. Analyst 2012; 137:365-9. [DOI: 10.1039/c1an15874k] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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246
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Singh P, Singh K, Jairajpuri MA. Energetics of Hydrogen Bond Switch, Residue Burial and Cavity Analysis Reveals Molecular Basis of Improved Heparin Binding to Antithrombin. J Biomol Struct Dyn 2011; 29:339-50. [DOI: 10.1080/07391102.2011.10507389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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247
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Al-Horani RA, Liang A, Desai UR. Designing nonsaccharide, allosteric activators of antithrombin for accelerated inhibition of factor Xa. J Med Chem 2011; 54:6125-38. [PMID: 21800826 PMCID: PMC3165067 DOI: 10.1021/jm2008387] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Antithrombin is a key regulator of coagulation and prime target of heparins, clinically used anticoagulants. Heparins induce a two-step conformational activation of antithrombin, a process that has remained challenging to target with molecules devoid of the antithrombin-binding pentasaccharide DEFGH. Computational screening of a focused library led to the design of two tetra-sulfated N-arylacyl tetrahydroisoquinoline variants as potential nonsaccharide activators of antithrombin. A high yielding synthetic scheme based on Horner-Wadsworth-Emmons or Pictet-Spengler reactions was developed to facilitate the functionalization of the tetrahydoisoquinoline ring, which upon further amidation, deprotection, and sulfation gave the targeted nonsaccharide activators. Spectrofluorometric measurement of affinity displayed antithrombin binding affinities in the low to high micromolar range at pH 6.0, I 0.05, 25 °C. Measurement of second-order rate constants of antithrombin inhibition of factor Xa in the presence and absence of the designed activators showed antithrombin activation in the range of 8-80-fold in the pH 6.0 buffer. This work puts forward 20c, a novel tetra-sulfated N-arylacyl tetrahydroisoquinoline-based molecule, that activates AT only 3.8-fold less than that achieved with DEFGH, suggesting a strong possibility of rationally designing sulfated organic molecules as clinically relevant AT activators.
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Affiliation(s)
- Rami A. Al-Horani
- Department of Medicinal Chemistry and Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, VA 23298
| | - Aiye Liang
- Department of Medicinal Chemistry and Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, VA 23298
| | - Umesh R. Desai
- Department of Medicinal Chemistry and Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, VA 23298
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248
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Nieto L, Canales Á, Giménez-Gallego G, Nieto PM, Jiménez-Barbero J. Conformational selection of the AGA*IA(M) heparin pentasaccharide when bound to the fibroblast growth factor receptor. Chemistry 2011; 17:11204-9. [PMID: 21922554 DOI: 10.1002/chem.201101000] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Indexed: 11/10/2022]
Abstract
The interaction of the synthetic pentasaccharide AGA*IA(M) (GlcNS,6S-GlcA-GlcNS,3S,6S-IdoA2S-GlcNS,6S-Me) with the extracellular Ig2 domain of the fibroblast growth factor receptor (FGFR2) has been studied by NMR and computational methods. Analysis of the heparin pentasaccharide in the free state and in the complex indicates the existence of a conformational selection process. Although an equilibrium exists between the (1)C(4) and (2)S(0) conformers (ratio 60:40) of the 2-O-sulfo-α-L-iduronate ring (IdoA2S) in the free state, FGFR2 selects only the unique twisted-boat (2)S(0) conformation of this IdoA2S residue. In addition, the protein residues involved in the binding with AGA*IA(M) have also been characterized. The NMR results obtained, from both the ligand and protein perspective, were employed to model the bound conformation of the pentasaccharide by a combined docking and molecular dynamic simulation approach.
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Affiliation(s)
- Lidia Nieto
- Chemical and Physical Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
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249
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Xu X, Jha AK, Duncan RL, Jia X. Heparin-decorated, hyaluronic acid-based hydrogel particles for the controlled release of bone morphogenetic protein 2. Acta Biomater 2011; 7:3050-9. [PMID: 21550426 DOI: 10.1016/j.actbio.2011.04.018] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 04/14/2011] [Accepted: 04/19/2011] [Indexed: 10/18/2022]
Abstract
We are interested in developing hydrophilic particulate systems that are capable of sequestering growth factors, regulating their release and potentiating their biological functions. To this end heparin (HP)-decorated, hyaluronic acid (HA)-based hydrogel particles (HGPs) were synthesized using an inverse emulsion polymerization technique employing divinyl sulfone as the crosslinker. By varying the feed composition of the aqueous phase the amount of HP integrated in the particles can be systematically tuned. The resulting microscopic particles are spherical in shape and contain nanosized pores suitable for growth factor encapsulation. The covalently immobilized HP retained its ability to bind bone morphogenetic protein-2 (BMP-2) specifically, and its release kinetics can be adjusted by tuning the particle composition. Compared with pure HA particles the hybrid HA/HP HGPs show a higher BMP-2 loading capacity. While BMP-2 was released from HA HGPs with a significant initial burst, a near zero order release kinetics was observed from HA/HP hybrid particles with an optimized heparin content of 0.55 μg per mg HGPs. The ability of HA/HP hybrid particles to present BMP-2 in a controlled manner, combined with the innate bioactivity of HA, induced robust and consistent chondrogenic differentiation of murine mesenchymal stem cells, as shown by up-regulation of the mRNA levels of chondrogenic markers and the production of cartilage-specific extracellular matrix components. The simplicity of the particle synthesis, combined with the defined biological activities of the constituent building blocks, renders the HP-decorated, HA-based hydrogel particle system an attractive candidate for the sustained release of BMP-2, possibly for cartilage repair and regeneration.
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250
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Pol-Fachin L, Franco Becker C, Almeida Guimarães J, Verli H. Effects of glycosylation on heparin binding and antithrombin activation by heparin. Proteins 2011; 79:2735-45. [PMID: 21769943 DOI: 10.1002/prot.23102] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2010] [Revised: 05/31/2011] [Accepted: 06/07/2011] [Indexed: 11/06/2022]
Abstract
Antithrombin (AT), a serine protease inhibitor, circulates in blood in two major isoforms, α and β, which differ in their amount of glycosylation and affinity for heparin. After binding to this glycosaminoglycan, the native AT conformation, relatively inactive as a protease inhibitor, is converted to an activated form. In this process, β-AT presents the higher affinity for heparin, being suggested as the major AT glycoform inhibitor in vivo. However, either the molecular basis demonstrating the differences in heparin binding to both AT isoforms or the mechanism of its conformational activation are not fully understood. Thus, the present work evaluated the effects of glycosylation and heparin binding on AT structure, function, and dynamics. Based on the obtained data, besides the native and activated forms of AT, an intermediate state, previously proposed to exist between such conformations, was also spontaneously observed in solution. Additionally, Asn135-linked oligosaccharide caused a bending in AT-bounded heparin, moving such polysaccharide away from helix D, which supports its reduced affinity for α-AT. The obtained data supported the proposal of an atomic-level, solvent and amino acid residues accounting, putative model for the transmission of the conformational signal from heparin binding exosite to β-sheet A and the reactive center loop, also supporting the identification of differences in such transmission between the serpin glycoforms involving helix D, where the Asn135-linked oligosaccharide stands. Such intramolecular rearrangements, together with heparin dynamics over AT surface, may support an atomic-level explanation for the Asn135-linked glycan influence over heparin binding and AT activation.
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Affiliation(s)
- Laercio Pol-Fachin
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Av Bento Gonçalves 9500, CP 15005, Porto Alegre 91500-970, RS, Brazil
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