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Church FC. Suggestions on leading an academic research laboratory group. Open Life Sci 2022; 17:599-609. [PMID: 35800075 PMCID: PMC9202531 DOI: 10.1515/biol-2022-0061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 02/24/2022] [Accepted: 03/25/2022] [Indexed: 11/15/2022] Open
Abstract
This commentary is about running an academic research laboratory group, including some reflections, memories, and tips on effectively managing such a group of scientists focused on one’s research. The author’s academic career has spanned from 1982 to 2022, including postdoctoral research associate through the rank of professor with tenure. Currently, the author is in the final year of 3 years of phased retirement. One must be willing to work hard at running a research laboratory. Also, stay focused on funding the laboratory tasks and publishing one’s work. Recruit the best people possible with advice from the collective laboratory group. Laboratory group members felt more like they were a part of a collective family than simply employees; however, what works best for the researcher is what matters. Several other points to discuss will include managing university roles, recruiting laboratory personnel, getting recognition, dealing with intellectual property rights, and publishing work. In closing, there are many more positives than negatives to leading a research laboratory group. Finally, one cannot replace the unforgettable memories and the legacy of a research laboratory group.
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Affiliation(s)
- Frank C. Church
- Department of Pathology and Laboratory Medicine, The University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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Gupta VK, Gowda LR. Alpha-1-proteinase inhibitor is a heparin binding serpin: molecular interactions with the Lys rich cluster of helix-F domain. Biochimie 2008; 90:749-61. [PMID: 18261994 DOI: 10.1016/j.biochi.2008.01.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 01/11/2008] [Indexed: 11/29/2022]
Abstract
Alpha-1-proteinase (alpha-1-PI) inhibitor is the major circulating serine protease inhibitor in humans. The porcine elastase and trypsin inhibitory activity of human and ovine alpha-1-PI is activated several fold in the presence of anti-coagulant heparin. The activation is allosteric and appears to be characterized by two steps of binding; a weak followed by a strong binding. The Kass for ovine and human alpha-1-PI inhibition of porcine pancreatic elastase was increased approximately 45 fold and 38 fold respectively. Using a combinatorial approach of multiple sequence alignment, surface topology, chemical modification and tryptic peptide mapping to identify the sequence of the heparin bound peptide; we demonstrate that heparin binds to the lysyl rich region of the F-helix of alpha-1-PI, which differs from that of heparin-antithrombin (AT) interactions. Molecular docking prediction using the MEDock algorithm approximates the three positively charged lysines (K154, K155, K174) of human alpha-1-PI in this interaction. This heparin alpha-1-PI interaction has been exploited to develop an affinity purification method, which can be used universally to obtain homogenous preparations of mammalian alpha-1-PIs useful for augmentation therapy. Collectively, all these findings imply that alpha-1-PI has a major role in regulating extra cellular protease activity and the physiological activator is heparin.
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Affiliation(s)
- Vivek Kumar Gupta
- Department of Protein Chemistry and Technology, Central Food Technological Research Institute, Mysore 570020, India
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4
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Abstract
Heparin is a major anticoagulant with activity mediated primarily through its interaction with antithrombin (AT). Heparan sulfate (HS), structurally related to heparin, binds a wide range of proteins of different functionality, taking part in various physiological and pathological processes. The heparin-AT complex, the most well understood facet of anticoagulation, serves as a prototypical example of the important role of heparin/HS in vascular biology. Extensive studies have identified common structural features in heparin/HS-binding sites of proteins. These include the elucidation of consensus sequences in proteins, patterns of clusters of basic and nonbasic residues, and common spatial arrangements of basic amino acids in the heparin-binding sites. Although these studies have provided valuable information, heparin/HS-binding proteins differ widely in structure. The prediction of heparin/HS-binding proteins from sequence information is not currently possible, and elucidation of protein-binding sites requires the individual study of each glycosaminoglycan-protein complex. Thus, x-ray crystallography and site-directed mutagenesis experiments are among the most powerful tools, providing accurate structural information, facilitating the characterization of heparin-protein complexes. Heparin and structurally related heparan sulfate bind a large number of proteins, taking part in a wide range of biological processes, particularly ones involved in vascular biology. Heparin-binding domains share certain common structural features, but there is no absolute dependency on specific sequences or protein folds.
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Affiliation(s)
- Eva M Muñoz
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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Hermans JM, Haines DS, James PS, Jones R. Kinetics of inhibition of sperm beta-acrosin activity by suramin. FEBS Lett 2003; 544:119-22. [PMID: 12782300 DOI: 10.1016/s0014-5793(03)00488-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Sperm beta-acrosin activity is inhibited by suramin, a polysulfonated naphthylurea compound with therapeutic potential as a combined antifertility agent and microbicide. A kinetic analysis of enzyme inhibition suggests that three and four molecules of suramin bind to one molecule of ram and boar beta-acrosins respectively. Surface charge distribution models of boar beta-acrosin based on its crystal structure indicate several positively charged exosites that represent potential 'docking' regions for suramin. It is hypothesised that the spatial arrangement and distance between these exosites determines the capacity of beta-acrosin to bind suramin.
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Affiliation(s)
- Josephine M Hermans
- Department of Biochemistry and Molecular Biology, School of Pharmacy and Molecular Sciences, James Cook University, Townsville, Qld 4811, Australia.
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6
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Jairajpuri MA, Lu A, Desai U, Olson ST, Bjork I, Bock SC. Antithrombin III phenylalanines 122 and 121 contribute to its high affinity for heparin and its conformational activation. J Biol Chem 2003; 278:15941-50. [PMID: 12556442 DOI: 10.1074/jbc.m212319200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The dissociation equilibrium constant for heparin binding to antithrombin III (ATIII) is a measure of the cofactor's binding to and activation of the proteinase inhibitor, and its salt dependence indicates that ionic and non-ionic interactions contribute approximately 40 and approximately 60% of the binding free energy, respectively. We now report that phenylalanines 121 and 122 (Phe-121 and Phe-122) together contribute 43% of the total binding free energy and 77% of the energy of non-ionic binding interactions. The large contribution of these hydrophobic residues to the binding energy is mediated not by direct interactions with heparin, but indirectly, through contacts between their phenyl rings and the non-polar stems of positively charged heparin binding residues, whose terminal amino and guanidinium groups are thereby organized to form extensive and specific ionic and non-ionic contacts with the pentasaccharide. Investigation of the kinetics of heparin binding demonstrated that Phe-122 is critical for promoting a normal rate of conformational change and stabilizing AT*H, the high affinity-activated binary complex. Kinetic and structural considerations suggest that Phe-122 and Lys-114 act cooperatively through non-ionic interactions to promote P-helix formation and ATIII binding to the pentasaccharide. In summary, although hydrophobic residues Phe-122 and Phe-121 make minimal contact with the pentasaccharide, they play a critical role in heparin binding and activation of antithrombin by coordinating the P-helix-mediated conformational change and organizing an extensive network of ionic and non-ionic interactions between positively charged heparin binding site residues and the cofactor.
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Affiliation(s)
- Mohamad Aman Jairajpuri
- Departments of Medicine and Bioengineering, Health Science Center, University of Utah, 50 N. Medical Drive, Salt Lake City, UT 84132, USA
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Howes E, Pascall JC, Engel W, Jones R. Interactions between mouse ZP2 glycoprotein and proacrosin; a mechanism for secondary binding of sperm to the zona pellucida during fertilization. J Cell Sci 2001; 114:4127-36. [PMID: 11739644 DOI: 10.1242/jcs.114.22.4127] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The mouse zona pellucida glycoprotein, mZP2, is thought to be the secondary receptor on eggs for retention of acrosome-reacted sperm during fertilization. Here, we present evidence that one of its complementary binding proteins on sperm is proacrosin/acrosin. mZP2 binds to proacrosin null sperm considerably less effectively than to wild-type sperm. Binding is mediated by a strong ionic interaction between polysulphate groups on mZP2 and basic residues on an internal proacrosin peptide. The stereochemistry of both sulphate groups and basic amino acids determines the specificity of binding. Structurally relevant sulphated polymers and suramin, a polysulphonated anticancer drug, compete with mZP2 for complementary binding sites on proacrosin/acrosin in solid-phase binding assays. The same competitors also displace attached sperm from the zona pellucida of eggs in an in vitro fertilization system. This combination of genetic, biochemical and functional data supports the hypothesis that mZP2-proacrosin interactions are important for retention of acrosome-reacted sperm on the egg surface during fertilization. Safe mimetics of suramin have potential as non-steroidal antifertility agents.
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Affiliation(s)
- E Howes
- Signalling Programme, The Babraham Institute, Cambridge CB2 4AT, UK
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Carrell R, Lomas D, Stein P, Whisstock J. Dysfunctional variants and the structural biology of the serpins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1998; 425:207-22. [PMID: 9433503 DOI: 10.1007/978-1-4615-5391-5_20] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- R Carrell
- Department of Haematology, University of Cambridge, England
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Ersdal-Badju E, Lu A, Zuo Y, Picard V, Bock SC. Identification of the antithrombin III heparin binding site. J Biol Chem 1997; 272:19393-400. [PMID: 9235938 DOI: 10.1074/jbc.272.31.19393] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The heparin binding site of the anticoagulant protein antithrombin III (ATIII) has been defined at high resolution by alanine scanning mutagenesis of 17 basic residues previously thought to interact with the cofactor based on chemical modification experiments, analysis of naturally occurring dysfunctional antithrombins, and proximity to helix D. The baculovirus expression system employed for this study produces antithrombin which is highly similar to plasma ATIII in its inhibition of thrombin and factor Xa and which resembles the naturally occurring beta-ATIII isoform in its interactions with high affinity heparin and pentasaccharide (Ersdal-Badju, E., Lu, A., Peng, X., Picard, V., Zendehrouh, P., Turk, B., Björk, I., Olson, S. T., and Bock, S. C. (1995) Biochem. J. 310, 323-330). Relative heparin affinities of basic-to-Ala substitution mutants were determined by NaCl gradient elution from heparin columns. The data show that only a subset of the previously implicated basic residues are critical for binding to heparin. The key heparin binding residues, Lys-11, Arg-13, Arg-24, Arg-47, Lys-125, Arg-129, and Arg-145, line a 50-A long channel on the surface of ATIII. Comparisons of binding residue positions in the structure of P14-inserted ATIII and models of native antithrombin, derived from the structures of native ovalbumin and native antichymotrypsin, suggest that heparin may activate antithrombin by breaking salt bridges that stabilize its native conformation. Specifically, heparin release of intramolecular helix D-sheet B salt bridges may facilitate s123AhDEF movement and generation of an activated species that is conformationally primed for reactive loop uptake by central beta-sheet A and for inhibitory complex formation. In addition to providing a structural explanation for the conformational change observed upon heparin binding to antithrombin III, differences in the affinities of native, heparin-bound, complexed, and cleaved ATIII molecules for heparin can be explained based on the identified binding site and suggest why heparin functions catalytically and is released from antithrombin upon inhibitory complex formation.
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Affiliation(s)
- E Ersdal-Badju
- Temple University School of Medicine, Department of Microbiology/Immunology and The Sol Sherry Thrombosis Research Center, Philadelphia, Pennsylvania 19140, USA
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11
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Meagher JL, Huntington JA, Fan B, Gettins PG. Role of arginine 132 and lysine 133 in heparin binding to and activation of antithrombin. J Biol Chem 1996; 271:29353-8. [PMID: 8910598 DOI: 10.1074/jbc.271.46.29353] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The binding of heparin to antithrombin greatly accelerates the rate of inhibition of the target proteinases thrombin and factor Xa. Acceleration of the rate of inhibition of factor Xa involves a conformational change in antithrombin that is translated from the heparin binding site to the reactive center loop. A mechanism has been proposed for generation and propagation of the conformational change in which the binding of the negatively charged heparin reduces ionic repulsions between positively charged residues on and adjacent to the D-helix in the heparin binding site of antithrombin (van Boeckel, C. A. A., Grootenhuis, P. D. J., and Visser, A. (1994) Nature Struct. Biol. 1, 423-425). This charge neutralization is proposed to elongate the D-helix and initiate the conformational change which is then translated to the reactive center loop. Several basic residues, including arginine 132 and lysine 133, were predicted to be important both in heparin binding and in this mechanism of heparin activation. To test both the helix extension mechanism and the role of these two residues in heparin binding and factor Xa inhibition, we individually changed arginine 132 and lysine 133 to uncharged methionine by site-directed mutagenesis. The Kd values for binding of R132M and K133M variants to the high affinity pentasaccharide were weakened only 2.3- and 4.5-fold respectively, suggesting a location for R132 and K133 peripheral to the main pentasaccharide binding site. However, the Kd values for long chain high affinity heparin were weakened at least 17-fold for both R132M and K133M, indicating involvement of each residue in binding extended chain heparin species. These reductions in affinity were ionic strength-dependent. The rates of inhibition of factor Xa and thrombin by each variant, however, were indistinguishable from those of control antithrombin, and the accelerations of the rate of inhibition produced by heparin were normal. We conclude that neither arginine 132 nor lysine 133 plays an important role in the binding of heparin pentasaccharide or in the mechanism of heparin activation, suggesting that D-helix extension through charge neutralization is not the mechanism for transmission of conformational change from the heparin binding site to the reactive center region. Arginine 132 and lysine 133 do, however, play a role in tight binding of longer chain heparin species through ionic interactions.
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Affiliation(s)
- J L Meagher
- Department of Biochemistry, University of Illinois, Chicago, Illinois 60612, USA
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12
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Kridel SJ, Chan WW, Knauer DJ. Requirement of lysine residues outside of the proposed pentasaccharide binding region for high affinity heparin binding and activation of human antithrombin III. J Biol Chem 1996; 271:20935-41. [PMID: 8702852 DOI: 10.1074/jbc.271.34.20935] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Variant forms of human antithrombin III with glutamine or threonine substitutions at Lys114, Lys125, Lys133, Lys136, and Lys139 were expressed in insect cells to evaluate their roles in heparin binding and activation. Recombinant native ATIII and all of the variants had very similar second order rate constants for thrombin inhibition in the absence of heparin, ranging from 1.13 x 10(5) M-1min-1 to 1.66 x 10(5) M-1min-1. Direct binding studies using 125I-flouresceinamine-heparin yielded a Kd of 6 nM for the recombinant native ATIII and K136T, whereas K114Q and K139Q bound heparin so poorly that a Kd could not be determined. K125Q had a moderately reduced affinity. Heparin binding affinity correlated directly with heparin cofactor activity. Recombinant native ATIII was nearly identical to plasma-purified ATIII, whereas K114Q and K139Q were severely impaired in heparin cofactor activity. K125Q and K136T were only slightly impaired. Based on these data, Lys114 and Lys139, which are outside of the putative pentasaccharide binding site, play pivotal roles in the high affinity binding of heparin to ATIII and the activation of thrombin inhibitory activity.
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Affiliation(s)
- S J Kridel
- Department of Developmental and Cell Biology, School of Biological Sciences, University of California, Irvine, California 92717, USA
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13
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Caldwell EE, Nadkarni VD, Fromm JR, Linhardt RJ, Weiler JM. Importance of specific amino acids in protein binding sites for heparin and heparan sulfate. Int J Biochem Cell Biol 1996; 28:203-16. [PMID: 8729007 DOI: 10.1016/1357-2725(95)00123-9] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Heparin and heparan sulfate bind a variety of proteins and peptides to regulate many biological activities. Past studies have examined a limited number of established heparin binding sites and have focused on basic amino acids when modeling binding site structural motifs. This study examines the prevalence of individual amino acids in peptides binding to heparin or heparan sulfate. A 7-mer random peptide library was synthesized using the 20 common amino acids. This 7-mer library was affinity separated using both heparin and heparan sulfate-Sepharose. Bound peptide populations were eluted with a salt step gradient (pH 7) and analysed for amino acid composition. Peptides released from heparin-Sepharose by 0.3 M NaCl were enriched in arginine, lysine, glycine and serine; and depleted in methionine and phenylalanine. In contrast, peptides released from heparan sulfate-Sepharose were enriched in arginine, glycine, serine, and proline (at 0.15 M NaCl). These peptides were depleted in histidine, isoleucine, methionine (not detectable) and phenylalanine. In the heparin binding sites of proteins, which have been published, the enriched amino acids were arginine, lysine and tyrosine. Depleted amino acids include aspartic acid, glutamic acid, glutamine, alanine, glycine, phenylalanine, serine, threonine and valine. This study demonstrates that heparin and heparan sulfate bind different populations of peptide sequences. The differences in amino acid composition indicate that the positive charge density and spacing requirements differ for peptides binding these two glycosaminoglycans.
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Affiliation(s)
- E E Caldwell
- Department of Internal Medicine, University of Iowa, Iowa City 52242, USA
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Carrell RW, Stein PE. The biostructural pathology of the serpins: critical function of sheet opening mechanism. BIOLOGICAL CHEMISTRY HOPPE-SEYLER 1996; 377:1-17. [PMID: 8929809 DOI: 10.1515/bchm3.1996.377.1.1] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The serpins illustrate the way in which the study of a protein family as a whole can clarify the functions of its individual members. Although the individual serpins have become remarkably diversified by evolution they all share a common structural pathology. We have previously shown how plotting of the dysfunctional natural mutations of the serpins on a template structure defines the domains controlling the mobility of the reactive centre loop of the molecule. Here we compare these natural mutations with reciprocal mutations in recombinants that restore the inhibitory stability of a labile member of the family, plasminogen activator inhibitor-1 (PAI-1). The combined results emphasise the critical part played by residues involved in the sliding movement that opens the A-sheet to allow reactive loop insertion. It is concluded that changes in these residues provide the prime explanation for the ready conversion of PAI-1 to the inactive latent state. The consistency of the overall results gives confidence in predicting the likely consequences of mutations in individual serpins. In particular the two common polymorphic mutations present in human angiotensinogen are likely to affect molecular stability and hence may be contributory factors to the observed association with vascular disease.
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Affiliation(s)
- R W Carrell
- Department of Haematology, University of Cambridge, UK
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Abstract
Antithrombin, the main inhibitor of thrombosis in blood, is bound and activated by the heparin-like side-chains that line the small vasculature. We now have good depictions of the heparin-binding site on antithrombin, and of the way in which mutations at this site cause thrombotic disease. The interaction of heparin with antithrombin is, however, a kinetic one, with binding being followed by formation of a complex with thrombin and then release from the heparin. Our understanding of the processes involved is currently based on crystallographic models but, for a mobile mechanism, these merely provide snapshots - what is needed is a movie.
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Affiliation(s)
- R Carrell
- Department of Haematology, University of Cambridge, MRC Centre, Hills Road, Cambridge, UK
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Fan B, Turko IV, Gettins PG. Lysine-heparin interactions in antithrombin. Properties of K125M and K290M,K294M,K297M variants. Biochemistry 1994; 33:14156-61. [PMID: 7947827 DOI: 10.1021/bi00251a026] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Lysine residues in two different regions of antithrombin have been proposed to be involved in heparin binding and heparin-mediated acceleration of proteinase inhibition. Lysine 125 has been implicated as an essential heparin binding residue from chemical modification studies [Peterson, C. B., Noyes, C. M., Pecon, J. M., Church, F. C., & Blackburn, M. N. (1987) J. Biol. Chem. 262, 8061-8065] whereas lysines 290, 294, and 297 have been proposed from model building studies to constitute the heparin binding site [Villanueva, G. B. (1984) J. Biol. Chem. 259, 2531-2536]. To evaluate both of these proposals, we have prepared two variant human antithrombins, K125M and K290M,K294M,K297M, in which these lysines have been changed by site-directed mutagenesis to methionines. The K290M,K294M,K297M variant had properties very similar to those of wild-type recombinant antithrombin in affinity for heparin, and in rates of inhibition of thrombin and factor Xa. In contrast, K125M antithrombin had reduced affinity for both heparin pentasaccharide and full-length heparin, corresponding to delta delta Gs of 3.1 and 2.0 kcal mol-1, respectively. However, this variant was still able to inhibit both thrombin and factor Xa. Whereas the rate of thrombin inhibition was similar to that of wild-type antithrombin, the rate of factor Xa inhibition was enhanced between 2- and 3-fold, suggesting a role for lysine 125 in the allosteric coupling between the heparin binding site and the reactive center region. At saturation with either heparin pentasaccharide or full-length high-affinity heparin, the rates of inhibition of both proteinases were similar to those of wild-type antithrombin for both the K125M and K290M,K294M,K297M variants.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- B Fan
- Department of Biochemistry, University of Illinois-Chicago 60612
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17
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Stone SR, Brown-Luedi ML, Rovelli G, Guidolin A, McGlynn E, Monard D. Localization of the heparin-binding site of glia-derived nexin/protease nexin-1 by site-directed mutagenesis. Biochemistry 1994; 33:7731-5. [PMID: 8011637 DOI: 10.1021/bi00190a028] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Recombinant rat glia-derived nexin was expressed in insect cells using the baculovirus system. The kinetics for the inhibition of thrombin by this recombinant material were indistinguishable from those observed with natural glia-derived nexin and recombinant nexin expressed in yeast. In addition, the dependence of the rate of inactivation on the concentration of heparin was similar for the three preparations. At the optimal heparin concentration, the association rate constant was 330-fold higher than that observed in the absence of heparin. A putative heparin-binding site is found in glia-derived nexin between residues 71 and 86; heparin-binding sites are found in homologous regions of antithrombin III and heparin cofactor II. Lysines in this region were mutated to glutamates, and the kinetics for the inhibition of thrombin by mutant proteins were determined. Concurrent mutation of all seven lysines in this region (residues 71, 74, 75, 78, 83, 84, and 86) did not affect the rate constant for the association of glia-derived nexin with thrombin in the absence of heparin, but it resulted in complete loss of the heparin acceleration of the rate of association. Mutations of residues 83, 84, and 86 together also caused a marked decrease in the acceleration by heparin of the reaction between glia-derived nexin and thrombin. These results support the hypothesis that the heparin-binding sites of glia-derived nexin, antithrombin III, and heparin cofactor II are found in homologous regions of the molecules. Heparin was also found to potentiate the ability of wild-type glia-derived nexin to inhibit the thrombin-induced retraction of neurites from neuroblastoma NB2a cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S R Stone
- Department of Haematology, University of Cambridge, MRC Centre, U.K
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18
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Dawes J, James K, Lane DA. Conformational change in antithrombin induced by heparin probed with a monoclonal antibody against the 1C/4B region. Biochemistry 1994; 33:4375-83. [PMID: 7512382 DOI: 10.1021/bi00180a035] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A murine monoclonal antibody (MAb) raised against a covalent antithrombin-heparin complex was used to probe the conformational change resulting when the serpin antithrombin binds to heparin. This MAb completely inhibited the progressive activity of antithrombin against thrombin. However, although the MAb remained bound to antithrombin in the presence of heparin, it did not significantly inhibit heparin cofactor activity against thrombin, and increasing concentrations of the antithrombin-binding pentasaccharide progressively unblocked the inhibitory action of the MAb. The MAb bound to antithrombin without affecting either heparin-binding affinity or heparin-induced fluorescence enhancement, and it did not convert antithrombin from inhibitor to substrate. The MAb failed to interact with reduced and S-carboxymethylated antithrombin, indicating the conformational nature of its epitope. Antithrombin variants with N-terminal substitutions (Arg47-->Cys or His, Leu99-->Phe, Arg129-->Gln) modifying heparin binding, and C-terminal substitutions affecting the reactive site (Arg393-->Cys) or resulting in substrate-variant antithrombin (Ala384-->Pro), were all recognized normally, as were normal reactive site cleaved antithrombin and the thrombin-antithrombin complex. However, interaction of the MAb with antithrombin was reduced by several substitution mutations (Phe402-->Cys, Phe402-->Ser, Phe402-->Leu, Ala404-->Thr, Pro407-->Thr) in the 402-407 sequence which codes for amino acid residues of strand 1C and the polypeptide leading to strand 4B. Pro429-->Leu also blocks recognition [Olds et al. (1992) Blood 79, 1206-1212], and this residue is believed to be spatially approximated to strand 1C.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Dawes
- Heart Research Institute, Camperdown, NSW, Australia
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Abstract
Human antithrombin is the major inhibitor of the coagulation serine proteases accounting for approximately 80% of the thrombin inhibitory activity of plasma. It is a member of the serpin family of serine protease inhibitors and in common with some other members of this family it undergoes a dramatic increase in its inhibitory activity in the presence of heparin and other sulphated glycosaminoglycans. Two functional domains in antithrombin are recognised, the reactive site domain which interacts with the active site serine residue of the protease and the heparin binding domain. The gene for antithrombin has been cloned and its entire nucleotide sequence determined. A deficiency or functional abnormality of antithrombin may result in an increased risk of thromboembolic disease. Such deficiencies are estimated to affect as many as 1:300 of the general population and 3 to 5% of patients with thrombotic disease. On the basis of functional and immunological antithrombin assays, antithrombin deficiency may be subdivided into Types I and II. Type I disease is due to a wide variety of heterogeneous DNA mutations whilst in Type II disease missense mutations leading to single amino acid substitutions have been identified in all cases. Clinically, Type I antithrombin deficiency is associated with recurrent thromboembolic disease whereas in Type II deficiency the risk of thrombosis is closely related to the position of the mutation within the protein. Thus, heterozygotes with mutations within the heparin binding domain of antithrombin have a relatively low risk of thrombosis compared to those with mutations at or close to the reactive site of the molecule.
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Affiliation(s)
- D J Perry
- Department of Haematology, University of Cambridge, MRC Centre, UK
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Phillips J, Shirk R, Whinna H, Henriksen R, Church F. Inhibition of dysthrombins Quick I and II by heparin cofactor II and antithrombin. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53696-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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21
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Nishioka J, Suzuki K. The role of the COOH-terminal region of antithrombin III. Evidence that the COOH-terminal region of the inhibitor enhances the reactivity of thrombin and factor Xa with the inhibitor. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41658-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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22
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Olds RJ, Lane DA, Boisclair M, Sas G, Bock SC, Thein SL. Antithrombin Budapest 3. An antithrombin variant with reduced heparin affinity resulting from the substitution L99F. FEBS Lett 1992; 300:241-6. [PMID: 1555650 DOI: 10.1016/0014-5793(92)80854-a] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The molecular basis and functional properties of a variant antithrombin (AT) protein. AT Budapest 3, were studied. A single base substitution was identified in codon 99, CTC----TTC, altering the normal leucine to phenylalanine. The proband presented with a history of venous thrombotic disease and was found to be homozygous for the mutation. The variant protein demonstrated reduced heparin affinity and reduced antiproteinase activity in the presence of either unfractionated heparin or the AT-binding heparin pentasaccharide, when compared to normal AT. A small change in the isoelectric point was also identified. The substituted amino acid residue of AT Budapest 3 is located near to the proposed AT heparin binding site, and it is suggested that reduced heparin affinity of the variant protein may result from substitution-induced distortion of positive charge geometry in the binding site and/or changes in its position relative to the rest of the inhibitor molecule.
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Affiliation(s)
- R J Olds
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
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23
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van Boeckel CA, Grootenhuis PD, Haasnoot CA. Specificity in the recognition process between charged carbohydrates and proteins. Trends Pharmacol Sci 1991; 12:241-3. [PMID: 1949187 DOI: 10.1016/0165-6147(91)90561-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- C A van Boeckel
- Organon International, Scientific Development Group, Oss, The Netherlands
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24
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25
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Mejdoub H, Le Ret M, Boulanger Y, Maman M, Choay J, Reinbolt J. The complete amino acid sequence of bovine antithrombin (ATIII). JOURNAL OF PROTEIN CHEMISTRY 1991; 10:205-12. [PMID: 1930634 DOI: 10.1007/bf01024785] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Bovine antithrombin (ATIII) is a glycoprotein of Mr 56,600. Its primary structure was established using peptide sequences from five different digests. Bovine ATIII exhibits four glcosylation sites as well as human ATIII. The primary structures of bovine and human ATIII were compared: all the residues required for the integrity of the heparin-binding domain are strictly conserved. However, there are differences in the secondary structures of both proteins, bovine and human ATIII.
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Affiliation(s)
- H Mejdoub
- Laboratoire de Biochimie, Centre National de la Recherche Scientifique, Strasbourg, France
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26
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27
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Expression of biologically active human antithrombin III by recombinant baculovirus in Spodoptera frugiperda cells. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)67892-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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28
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29
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Ragg H, Ulshöfer T, Gerewitz J. Glycosaminoglycan-mediated leuserpin-2/thrombin interaction. Structure-function relationships. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)45717-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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30
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Owen BA, Owen WG. Interaction of factor Xa with heparin does not contribute to the inhibition of factor Xa by antithrombin III-heparin. Biochemistry 1990; 29:9412-7. [PMID: 2248954 DOI: 10.1021/bi00492a015] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Factor Xa modified by reductive methylation (greater than 92%) loses the capacity to bind heparin as determined both by gel chromatography and by sedimentation equilibrium ultracentrifugation. The kinetic properties of methylated factor Xa differ, with respect to KM and Vmax for a synthetic tripeptide substrate and for antithrombin III inhibition rate constants, from those of the unmodified enzyme. The 10,000-fold rate enhancement elicited by the addition of heparin to the antithrombin III inhibition reaction, however, is the same. The observed second-order rate constants (k"obs) for antithrombin III inhibition of factor Xa and methylated factor Xa are 3000 and 340 M-1 s-1, respectively, whereas k"obs values for the inhibition of factor Xa or methylated factor Xa with antithrombin III-heparin are 4 X 10(7) and 3 X 10(6) M-1 s-1, respectively. These findings provide direct evidence that the interaction of factor Xa with heparin is not involved in the heparin-enhanced inhibition of this enzyme.
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Affiliation(s)
- B A Owen
- Section of Hematology Research, Mayo Clinic and Foundation, Rochester, Minnesota 55905
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31
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Sedimentation study on the binding of fibrinogen or of antithrombin III with acidic polysaccharides including heparin. Polym Bull (Berl) 1990. [DOI: 10.1007/bf00294097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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32
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Sun XJ, Chang JY. Evidence that arginine-129 and arginine-145 are located within the heparin binding site of human antithrombin III. Biochemistry 1990; 29:8957-62. [PMID: 2271571 DOI: 10.1021/bi00490a011] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Arginyl residues of human antithrombin III have been implicated to involve in the heparin binding site [Jorgensen, A. M., Borders, C. L., & Fish, W. W. (1985) Biochem, J. 231, 59-63]. We have performed chemical modification of antithrombin with (p-hydroxyphenyl)glyoxal (HPG) in order to determine the locations of these arginine residues. Antithrombin was modified with 12 mM HPG in the absence and presence of heparin (2-fold by weight to antithrombin). In the absence of heparin, about 3-4 mol of arginines/mol of antithrombin were modified within 60 min, and the modification led to the loss of 95% of the inhibitor's heparin cofactor activity as well as heparin-induced fluorescence enhancement and 50% of its progressive inhibitory activity. In the presence of heparin, the extent of modification was diminished by 30% and modified antithrombin retained approximately 70% of its heparin cofactor activity. Peptide mapping and subsequent sequence analysis revealed that selective HPG modification occurred at Arg129 and Arg145 and that their modifications were protected upon binding of heparin to antithrombin. We conclude that Arg129 and Arg145 are situated within the heparin binding site of human antithrombin III.
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Affiliation(s)
- X J Sun
- Pharmaceuticals Research Laboratories, Ciba-Geigy Ltd., Basel, Switzerland
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33
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Mourey L, Samama JP, Delarue M, Choay J, Lormeau JC, Petitou M, Moras D. Antithrombin III: structural and functional aspects. Biochimie 1990; 72:599-608. [PMID: 2126464 DOI: 10.1016/0300-9084(90)90123-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Antithrombin III is a plasma glycoprotein responsible for thrombin inhibition in the blood coagulation cascade. The X-ray structure of its cleaved form has been determined and refined to 3.2 A resolution. The overall topology is similar to that of alpha 1-antitrypsin, another member of the serpin (serine protease inhibitor) superfamily. The biological activity of antithrombin III is mediated by a polysaccharide, heparin. The binding site of this effector is described. A possible structural transition from the native to the cleaved structure is discussed.
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Affiliation(s)
- L Mourey
- Laboratoire de Cristallographie Biologique, IBMC du CNRS, Strasbourg, France
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34
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Blinder MA, Tollefsen DM. Site-directed mutagenesis of arginine 103 and lysine 185 in the proposed glycosaminoglycan-binding site of heparin cofactor II. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)40228-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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35
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Samama JP, Delarue M, Mourey L, Choay J, Moras D. Crystallization and preliminary crystallographic data for bovine antithrombin III. J Mol Biol 1989; 210:877-9. [PMID: 2614848 DOI: 10.1016/0022-2836(89)90116-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Crystals of bovine antithrombin III were obtained in the presence of metal ions with ammonium sulphate as precipitating agent. Crystals belong to space group P4(1)2(1)2 or P4(3)2(1)2 with cell parameters a = b = 91.4 A, c = 383.1 A; there are two molecules per asymmetric unit. Electrophoresis experiments and amino acid sequence analysis of the N-terminal part of redissolved crystals suggest that the protein molecules are cleaved at the active site.
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Affiliation(s)
- J P Samama
- Laboratoire de Cristallographie Biologique, I.B.M.C. du C.N.R.S., Strasbourg, France
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36
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Church FC, Pratt CW, Noyes CM, Kalayanamit T, Sherrill GB, Tobin RB, Meade JB. Structural and functional properties of human α-thrombin, phosphopyridoxylated α-thrombin, and γT-thrombin. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)51482-4] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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37
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Ahmed H, Gabius HJ. Purification and properties of a Ca2+-independent sialic acid-binding lectin from human placenta with preferential affinity to O-acetylsialic acids. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)51520-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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38
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Sun XJ, Chang JY. The heparin and pentosan polysulfate binding sites of human antithrombin overlap but are not identical. EUROPEAN JOURNAL OF BIOCHEMISTRY 1989; 185:225-30. [PMID: 2478364 DOI: 10.1111/j.1432-1033.1989.tb15106.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Four sulfated polysaccharides (unfractioned heparin, low-molecular-mass heparin, heparan sulfate and pentosan polysulfate) were investigated for their abilities (a) to bind antithrombin, (b) to induce conformational change of the inhibitor and (c) to potentiate antithrombin inhibition of thrombin. The binding capacity was reflected by the shielding of the heparin binding site. This was characterized by the extent to which a polysaccharide could protect chemical modification of Lys-125 and Lys-136, two lysyl residues of antithrombin which have been implicated in heparin binding. The conformational change was measured by fluorescence enhancement and the increased accessibility of Lys-236 to chemical modification. Our results reveal that the events of polysaccharide binding, conformational change and the enhancement of inhibitory activity are not quantitatively interlinked. Compared to the unfractionated heparin on an equal mass basis, the low-molecular-mass heparin (molecular mass 4-6 kDa) binds more strongly to antithrombin, induces a greater conformational change (about twofold), but is less potent in accelerating the inhibitory activity. Both heparin and heparan sulfate shield Lys-125 and Lys-136 and induce a conformational change that leads to exposure of Lys-236 and an increased fluorescence. On the other hand, pentosan polysulfate protects only Lys-125 and causes no appreciable conformational change, although it is also capable of enhancing the antithrombin-thrombin interaction. These data clearly demonstrate that the heparin and pentosan polysulfate binding sites of antithrombin overlap (at Lys-125) but are not identical.
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Affiliation(s)
- X J Sun
- Pharmaceuticals Research Laboratories, Ciba-Geigy Ltd, Basel, Switzerland
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39
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Lane DA, Caso R. Antithrombin: structure, genomic organization, function and inherited deficiency. BAILLIERE'S CLINICAL HAEMATOLOGY 1989; 2:961-98. [PMID: 2688761 DOI: 10.1016/s0950-3536(89)80054-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Antithrombin is a major plasma protein inhibitor of proteinases generated during blood coagulation; it plays an important role in the regulation of thrombin in blood. The anticoagulant heparin greatly accelerates the rate of inactivation of proteinases by antithrombin, predominantly through its well defined, highly specific binding reaction with the inhibitor, but also through a less strictly defined interaction with some of the proteinases (such as thrombin). There is evidence for an analogous acceleratory mechanism in vivo, that functions by the binding of antithrombin to a subpopulation of heparan sulphate proteoglycans intercalated in the surface of endothelial cells. The location and structure of the gene for antithrombin are known. Both its overall organization and the structure of the subdomains of the expressed protein can be considered in terms of their relationships to a serine proteinase inhibitor superfamily, which is believed to have evolved from a common ancestor. The region of the antithrombin gene 5' to the coding region has been characterized. Unlike other members of the serpin family, there is no TATA-like promoter sequence. Two enhancer sequences have been identified that are homologous to enhancer regions of other genes. There are two polymorphisms: an intragenic polymorphism arising from a translationally silent A to G transition in codon 305, and a length polymorphism arising from the presence of 32 bp or 108 bp non-homologous sequences 345 bp upstream from the translation initiation codon. Inherited deficiency of antithrombin is associated with familial thromboembolism. The molecular genetic basis of some subtypes of deficiency is increasingly yielding to investigation. It is interesting to note that a number of mutations have been identified in CpG dinucleotides, supporting the suggestion that this dinucleotide sequence may represent a mutation hotspot in the human genome.
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40
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Heparin Binding Domain of Human Antithrombin III Inferred from the Sequential Reduction of Its Three Disulfide Linkages. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)60462-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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41
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Erdjument H, Lane DA, Panico M, Di Marzo V, Morris HR, Bauer K, Rosenberg RD. Antithrombin Chicago, amino acid substitution of arginine 393 to histidine. Thromb Res 1989; 54:613-9. [PMID: 2781509 DOI: 10.1016/0049-3848(89)90127-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Antithrombin Chicago is a functionally inactive antithrombin variant whose inheritance is associated with thrombotic disease. The variant antithrombin was isolated from plasma of the propositus by chromatography on heparin-Sepharose, followed by passage through thrombin-Sepharose to remove the normal antithrombin component that is present. A pool of fragments ("CNBr pool 4") containing the reactive site region was prepared from the reduced and S-carboxymethylated variant by cleavage with cyanogen bromide followed by reverse-phase HPLC. Sequential treatment of CNBr pool 4 with trypsin and V8 protease produced peptides whose molecular masses were then determined by fast atom bombardment mass spectrometry. The variant protein digests were characterised by a reduction of a peptide of mass 1086, corresponding to the normal antithrombin sequence Ala382-Arg393. However, they contained a peptide of mass 1748, which arises when Arg393 is replaced by His in the sequence Ala382-Arg399. It is concluded that the functional and clinical abnormalities of antithrombin Chicago are all probably caused by a single amino acid substitution, Arg393 to His.
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Affiliation(s)
- H Erdjument
- Department of Haematology, Charing Cross and Westminster Hospital Medical School, Hammersmith, London
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42
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Jordan RE, Nelson RM, Kilpatrick J, Newgren JO, Esmon PC, Fournel MA. Inactivation of Human Antithrombin by Neutrophil Elastase. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)81648-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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43
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Lane DA, Erdjument H, Thompson E, Panico M, Di Marzo V, Morris HR, Leone G, De Stefano V, Thein SL. A novel amino acid substitution in the reactive site of a congenital variant antithrombin. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)81785-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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44
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Pratt CW, Whinna HC, Meade JB, Treanor RE, Church FC. Physicochemical aspects of heparin cofactor II. Ann N Y Acad Sci 1989; 556:104-15. [PMID: 2660681 DOI: 10.1111/j.1749-6632.1989.tb22494.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- C W Pratt
- Department of Pathology, University of North Carolina, Chapel Hill 27599
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45
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46
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47
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Chang JY. Binding of Heparin to Human Antithrombin III Activates Selective Chemical Modification at Lysine 236. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)94038-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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48
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49
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Lane DA, Erdjument H, Flynn A, Di Marzo V, Panico M, Morris HR, Greaves M, Dolan G, Preston FE. Antithrombin Sheffield: amino acid substitution at the reactive site (Arg393 to His) causing thrombosis. Br J Haematol 1989; 71:91-6. [PMID: 2917133 DOI: 10.1111/j.1365-2141.1989.tb06280.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A Sheffield family with a predisposition towards thrombosis has been shown to have a functional abnormality of antithrombin. The abnormality was detected as reduced heparin cofactor activity, with normal antigenic levels of antithrombin. Crossed immunoelectrophoresis performed in the absence and presence of heparin was normal. The antithrombin was isolated by heparin Sepharose affinity chromatography. It had normal mobility on SDS polyacrylamide gel electrophoresis. However, the second order rate constant of inhibition of thrombin was about half that of normal, and this was compatible with a heterozygous abnormality involving the reactive site. The antithrombin was further purified by chromatography on thrombin-Sepharose (to remove the normal component), reduced, S-carboxymethylated and fragmented with cyanogen bromide. A pool containing the reactive site region was digested with trypsin and the molecular size of peptides generated determined by fast atom bombardment mass spectrometry. The two peptides adjacent to the Arg393-Ser394 bond of mass 2290 and 700 were almost absent from the mass spectrum, but an additional peptide of mass 2952 was present. Subdigestion with V8 protease reduced the mass of this peptide to 1748. These peptides generated by trypsin and V8 protease were almost identical to those obtained when another variant, antithrombin Glasgow, was treated in the same way (Erdjument et al, 1988). It is concluded that the molecular abnormality of antithrombin Sheffield is identical to that of antithrombin Glasgow, Arg393 to His.
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Affiliation(s)
- D A Lane
- Department of Haematology, Charing Cross and Westminster Medical School, London
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50
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Cardin AD, Weintraub HJ. Molecular modeling of protein-glycosaminoglycan interactions. ARTERIOSCLEROSIS (DALLAS, TEX.) 1989; 9:21-32. [PMID: 2463827 DOI: 10.1161/01.atv.9.1.21] [Citation(s) in RCA: 1044] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Forty-nine regions in 21 proteins were identified as potential heparin-binding sites based on the sequence organizations of their basic and nonbasic residues. Twelve known heparin-binding sequences in vitronectin, apolipoproteins E and B-100, and platelet factor 4 were used to formulate two search strings for identifying potential heparin-binding regions in other proteins. Consensus sequences for glycosaminoglycan recognition were determined as [-X-B-B-X-B-X-] and [-X-B-B-B-X-X-B-X-] where B is the probability of a basic residue and X is a hydropathic residue. Predictions were then made as to the heparin-binding domains in endothelial cell growth factor, purpurin, and antithrombin-III. Many of the natural sequences conforming to these consensus motifs show prominent amphipathic periodicities having both alpha-helical and beta-strand conformations as determined by predictive algorithms and circular dichroism studies. The heparin-binding domain of vitronectin was modeled and formed a hydrophilic pocket that wrapped around and folded over a heparin octasaccharide, yielding a complementary structure. We suggest that these consensus sequence elements form potential nucleation sites for the recognition of polyanions in proteins and may provide a useful guide in identifying heparin-binding regions in other proteins. The possible relevance of protein-glycosaminoglycans interactions in atherosclerosis is discussed.
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Affiliation(s)
- A D Cardin
- Merrell Dow Research Institute, Cincinnati, Ohio 45215
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