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Viswanathan V, Ahmad MI, Singh PK, Ahmad N, Sharma P, Sharma S, Singh TP. Structural evidence of the conversion of nitric oxide (NO) to nitrite ion (NO 2-) by lactoperoxidase (LPO): Structure of the complex of LPO with NO 2- at 1.89 Å resolution. J Inorg Biochem 2023; 247:112311. [PMID: 37421730 DOI: 10.1016/j.jinorgbio.2023.112311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/26/2023] [Accepted: 06/30/2023] [Indexed: 07/10/2023]
Abstract
Lactoperoxidase (LPO) is a heme containing mammalian enzyme which uses hydrogen peroxide (H2O2) to catalyze the conversion of substrates into oxidized products. LPO is found in body fluids and tissues such as milk, saliva, tears, mucosa and other body secretions. The previous structural studies have shown that LPO converts substrates, thiocyanate (SCN-) and iodide (I-) ions into oxidized products, hypothiocyanite (OSCN-) and hypoiodite (IO-) ions respectively. We report here a new structure of the complex of LPO with an oxidized product, nitrite (NO2-). This product was generated from NO using the two step reaction of LPO by adding hydrogen peroxide (H2O2) in the solution of LPO in 0.1 M phosphate buffer at pH 6.8 as the first step. In the second step, NO gas was added to the above mixture. This was crystallized using 20% (w/v) PEG-3350 and 0.2 M ammonium iodide at pH 6.8. The structure determination showed the presence of NO2- ion in the distal heme cavity of the substrate binding site of LPO. The structure also showed that the propionate group which is linked to pyrrole ring D of the heme moiety was disordered. Similarly, the side chain of Asp108, which is covalently linked to heme moiety, was also split into two components. As a result of these changes, the conformation of the side chain of Arg255 was altered allowing it to form new interactions with the disordered carboxylic group of propionate moiety. These structural changes are indicative of an intermediate state in the catalytic reaction pathway of LPO.
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Affiliation(s)
- V Viswanathan
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Md Irshad Ahmad
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Prashant K Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Nayeem Ahmad
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Pradeep Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Sujata Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Tej P Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India.
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Ghosh B, Roy N, Roy D, Mandal S, Mondal M, Dakua VK, Dutta A, Sen S, Kumar A, Chakraborty R, Roy MN. Exploring Inclusion Complex of an Antithyroid Drug (PTU) with α-Cyclodextrin for Innovative Applications by Physicochemical Approach Optimized by Molecular Docking. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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Baker S, Miguel RN, Thomas D, Powell M, Furmaniak J, Smith BR. Cryo-electron microscopy structures of human thyroid peroxidase (TPO) in complex with TPO antibodies. J Mol Endocrinol 2023; 70:JME-22-0149. [PMID: 36537574 PMCID: PMC9986399 DOI: 10.1530/jme-22-0149] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 12/20/2022] [Indexed: 01/13/2023]
Abstract
Determination of the structure of the extracellular domain of human thyroid peroxidase (hTPO) by cryo-electron microscopy (cryo-EM) is described. TPO, purified to homogeneity was complexed with the hTPO monoclonal autoantibody 2G4 Fab and also with a mouse monoclonal TPO antibody 4F5 Fab (which competes with autoantibody binding to TPO). Both complexes were analysed by cryo-EM. The two structures (global resolution 3.92 and 3.4 Å for the 2G4 complex and 4F5 complex, respectively) show TPO as a monomer with four domains; the N-terminal domain, the peroxidase domain (POD), the complement control protein (CCP)-like domain and the epidermal growth factor-like domain which are all visible in the structures. The relative positions of the domains are fixed with a disulphide bond between cysteine residues Cys146 in the POD and Cys756 in the CCP domain preventing significant flexibility of the molecule. The entrance to the enzyme active site, the haem group and the calcium binding site are clearly visible on the opposite side of the TPO molecule from the 2G4 and 4F5 binding sites. Extensive interactions are seen between TPO and the two antibodies which both bind to distinct epitopes on the POD domain, including some residues in the immunodominant region B mainly via different residues. However, the epitopes of the two antibodies contain three shared TPO residues. This is the first high-resolution structure of TPO to be reported and it should help guide the development of new inhibitors of TPO enzyme activity for therapeutic applications.
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Affiliation(s)
- Stuart Baker
- FIRS Laboratories, RSR Ltd, Parc Ty Glas, Llanishen, Cardiff, UK
| | | | - Daniel Thomas
- FIRS Laboratories, RSR Ltd, Parc Ty Glas, Llanishen, Cardiff, UK
| | - Michael Powell
- FIRS Laboratories, RSR Ltd, Parc Ty Glas, Llanishen, Cardiff, UK
| | | | - Bernard Rees Smith
- FIRS Laboratories, RSR Ltd, Parc Ty Glas, Llanishen, Cardiff, UK
- Correspondence should be addressed to B Rees Smith:
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Singh PK, Ahmad N, Yamini S, Singh RP, Singh AK, Sharma P, Smith ML, Sharma S, Singh TP. Structural evidence of the oxidation of iodide ion into hyper-reactive hypoiodite ion by mammalian heme lactoperoxidase. Protein Sci 2022; 31:384-395. [PMID: 34761444 PMCID: PMC8819834 DOI: 10.1002/pro.4230] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 02/03/2023]
Abstract
Lactoperoxidase (1.11.1.7, LPO) is a mammalian heme peroxidase found in the extracellular fluids of mammals including plasma, saliva, airway epithelial lining fluids, nasal lining fluid, milk, tears, gastric juices, and intestinal mucosa. To perform its innate immune action against invading microbes, LPO utilizes hydrogen peroxide (H2 O2 ) to convert thiocyanate (SCN- ) and iodide (I- ) ions into the oxidizing compounds hypothiocyanite (OSCN- ) and hypoiodite (IO- ). Previously determined structures of the complexes of LPO with SCN- , OSCN- , and I- show that SCN- and I- occupy appropriate positions in the distal heme cavity as substrates while OSCN- binds in the distal heme cavity as a product inhibitor. We report here the structure of the complex of LPO with IO- as the first structural evidence of the conversion of iodide into hypoiodite by LPO. To obtain this complex, a solution of LPO was first incubated with H2 O2 , then mixed with ammonium iodide solution and the complex crystallized by the addition of PEG-3350, 20% (wt/vol). These crystals were used for X-ray intensity data collection and structure analysis. The structure determination revealed the presence of four hypoiodite ions in the substrate binding channel of LPO. In addition to these, six other hypoiodite ions were observed at different exterior sites. We surmise that the presence of hypoiodite ions in the distal heme cavity blocks the substrate binding site and inhibits catalysis. This was confirmed by activity experiments with the colorimetric substrate, ABTS (2,2'-azino-bis(3-ethylbenzthiazoline-sulfonic acid)), in the presence of hypoiodite and iodide ions.
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Affiliation(s)
- Prashant K. Singh
- Department of BiophysicsAll India Institute of Medical SciencesNew DelhiIndia
| | - Nayeem Ahmad
- Department of BiophysicsAll India Institute of Medical SciencesNew DelhiIndia
| | - Shavait Yamini
- Department of BiophysicsAll India Institute of Medical SciencesNew DelhiIndia
| | - Rashmi P. Singh
- Department of BiophysicsAll India Institute of Medical SciencesNew DelhiIndia
| | - Amit K. Singh
- Department of BiophysicsAll India Institute of Medical SciencesNew DelhiIndia
| | - Pradeep Sharma
- Department of BiophysicsAll India Institute of Medical SciencesNew DelhiIndia
| | | | - Sujata Sharma
- Department of BiophysicsAll India Institute of Medical SciencesNew DelhiIndia
| | - Tej P. Singh
- Department of BiophysicsAll India Institute of Medical SciencesNew DelhiIndia
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Xiao J, Wang J, Gan R, Wu D, Xu Y, Peng L, Geng F. Quantitative N-glycoproteome analysis of bovine milk and yogurt. Curr Res Food Sci 2022; 5:182-190. [PMID: 35072106 PMCID: PMC8763629 DOI: 10.1016/j.crfs.2022.01.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 12/25/2021] [Accepted: 01/05/2022] [Indexed: 12/02/2022] Open
Abstract
Post-translational modification structure of food's proteins might be changed during processing, thereby affecting the nutritional characteristics of the food product. In this study, differences in protein N-glycosylation patterns between milk and yogurt were quantitatively compared based on glycopeptide enrichment, liquid chromatography separation, and tandem mass spectrometry analysis. A total of 181 N-glycosites were identified, among which 142 were quantified in milk and yogurt. Significant alterations in the abundance of 13 of these N-glycosites were evident after the fermentation of milk into yogurt. Overall, the N-glycosylation status of the majority of milk proteins remained relatively unchanged in yogurt, suggesting that their conformations, activities, and functions were maintained despite the fermentation process. Among the main milk proteins, N241 of cathepsin D and N358 of lactoperoxidase were markedly reduced after undergoing lactic acid fermentation to produce yogurt. Furthermore, a comparative analysis of current and previously reported N-glycoproteomic data revealed heterogeneity in the N-glycosylation of milk proteins. To sum up, a quantitative comparison of the N-glycoproteomes of milk and yogurt was presented here for the first time, providing evidence that the fermentation process of yogurt could cause changes in the N-glycosylation of certain milk proteins. 181 N-glycosites from 118 N-glycoproteins were identified in milk and yogurt. 13 N-glycosites changed significantly after fermentation of milk into yogurt. N241 of cathepsin D and N358 of lactoperoxidase was markedly reduced in yogurt. Heterogeneity of N-glycosylation of milk protein has been documented.
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Affiliation(s)
- Jing Xiao
- Key Laboratory of Coarse Cereal Processing (Ministry of Agriculture and Rural Affairs), School of Food and Biological Engineering, Chengdu University, Chengdu, 610106, China
| | - Jinqiu Wang
- Key Laboratory of Coarse Cereal Processing (Ministry of Agriculture and Rural Affairs), School of Food and Biological Engineering, Chengdu University, Chengdu, 610106, China
| | - Renyou Gan
- Research Center for Plants and Human Health, Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, 610213, Sichuan, China
| | - Di Wu
- Key Laboratory of Coarse Cereal Processing (Ministry of Agriculture and Rural Affairs), School of Food and Biological Engineering, Chengdu University, Chengdu, 610106, China
| | - Yisha Xu
- Key Laboratory of Coarse Cereal Processing (Ministry of Agriculture and Rural Affairs), School of Food and Biological Engineering, Chengdu University, Chengdu, 610106, China
| | - Lianxin Peng
- Key Laboratory of Coarse Cereal Processing (Ministry of Agriculture and Rural Affairs), School of Food and Biological Engineering, Chengdu University, Chengdu, 610106, China
| | - Fang Geng
- Key Laboratory of Coarse Cereal Processing (Ministry of Agriculture and Rural Affairs), School of Food and Biological Engineering, Chengdu University, Chengdu, 610106, China
- Corresponding author.
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Singh PK, Sharma P, Bhushan A, Kaur P, Sharma S, Singh TP. Structure of a ternary complex of lactoperoxidase with iodide and hydrogen peroxide at 1.77 Å resolution. J Inorg Biochem 2021; 220:111461. [PMID: 33882424 DOI: 10.1016/j.jinorgbio.2021.111461] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/05/2021] [Accepted: 04/05/2021] [Indexed: 11/16/2022]
Abstract
Lactoperoxidase (LPO) is a mammalian heme peroxidase which catalyzes the conversion of thiocyanate (SCN¯) and iodide (I-) by hydrogen peroxide (H2O2) into antimicrobial hypothiocyanite (OSCN¯) and hypoiodite (IO-). The prosthetic heme group is covalently attached to LPO through two ester linkages involving conserved glutamate and aspartate residues. On the proximal side, His351 is coordinated to heme iron while His 109 is located in the substrate binding site on the distal heme side. We report here the first structure of the ternary complex of LPO with iodide (I-) and H2O2 at 1.77 Å resolution. LPO was crystallized with ammonium iodide and the crystals were soaked in the reservoir solution containing H2O2. Structure determination showed the presence of an iodide ion and a H2O2 molecule in the substrate binding site. The iodide ion occupied the position which is stabilized by the interactions with heme moiety, His109, Arg255 and Glu258 while H2O2 was held between the heme iron and His109. The presence of I- in the distal heme cavity seems to screen the positive charge of Arg255 thus suppressing the proton transfer from H2O2 to His109. This prevents compound I formation and allows trapping of a stable enzyme-substrate (LPO-I--H2O2) ternary complex. This stable geometrical arrangement of H2O2 in the distal heme cavity of LPO is similar to that of H2O2 in the structure of the transient intermediate of the palm tree heme peroxidase. The biochemical studies showed that the catalytic activity of LPO decreased when the samples of LPO were preincubated with ammonium iodide.
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Affiliation(s)
- Prashant K Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Pradeep Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Asha Bhushan
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Punit Kaur
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Sujata Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Tej P Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India.
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Singh PK, Pandey S, Rani C, Ahmad N, Viswanathan V, Sharma P, Kaur P, Sharma S, Singh TP. Potassium-induced partial inhibition of lactoperoxidase: structure of the complex of lactoperoxidase with potassium ion at 2.20 Å resolution. J Biol Inorg Chem 2021; 26:149-159. [PMID: 33427997 DOI: 10.1007/s00775-020-01844-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/07/2020] [Indexed: 11/30/2022]
Abstract
Lactoperoxidase, a heme-containing glycoprotein, catalyzes the oxidation of thiocyanate by hydrogen peroxide into hypothiocyanite which acts as an antibacterial agent. The prosthetic heme moiety is attached to the protein through two ester linkages via Glu258 and Asp108. In lactoperoxidase, the substrate-binding site is formed on the distal heme side. To study the effect of physiologically important potassium ion on the structure and function of lactoperoxidase, the fresh protein samples were isolated from yak (Bos grunniens) colostrum and purified to homogeneity. The biochemical studies with potassium fluoride showed a significant reduction in the catalytic activity. Lactoperoxidase was crystallized using 200 mM ammonium nitrate and 20% PEG-3350 at pH 6.0. The crystals of LPO were soaked in the solution of potassium fluoride and used for the X-ray intensity data collection. Structure determination at 2.20 Å resolution revealed the presence of a potassium ion in the distal heme cavity. Structure determination further revealed that the propionic chain attached to pyrrole ring C of the heme moiety, was disordered into two components each having an occupancy of 0.5. One component occupied a position similar to the normally observed position of propionic chain while the second component was found in the distal heme cavity. The potassium ion in the distal heme cavity formed five coordinate bonds with two oxygen atoms of propionic moiety, Nε2 atom of His109 and two oxygen atoms of water molecules. The presence of potassium ion in the distal heme cavity hampered the catalytic activity of lactoperoxidase.
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Affiliation(s)
- Prashant K Singh
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110 029, India
| | - Sadanand Pandey
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110 029, India
| | - Chitra Rani
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110 029, India
| | - Nayeem Ahmad
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110 029, India
| | - V Viswanathan
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110 029, India
| | - Pradeep Sharma
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110 029, India
| | - Punit Kaur
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110 029, India
| | - Sujata Sharma
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110 029, India
| | - Tej P Singh
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110 029, India.
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9
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Di Dato V, Barbarinaldi R, Amato A, Di Costanzo F, Fontanarosa C, Perna A, Amoresano A, Esposito F, Cutignano A, Ianora A, Romano G. Variation in prostaglandin metabolism during growth of the diatom Thalassiosira rotula. Sci Rep 2020; 10:5374. [PMID: 32214130 PMCID: PMC7096440 DOI: 10.1038/s41598-020-61967-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 02/28/2020] [Indexed: 02/03/2023] Open
Abstract
Prostaglandins (PGs) are hormone-like mediators in many physiological and pathological processes that are present in all vertebrates, in some terrestrial and aquatic invertebrates, and have also been identified in some macroalgae. They have recently been reported also in marine microalgae but their role as chemical mediators is largely unknown. Here we studied the expression pattern of the PG biosynthetic pathway during different growth phases of the centric diatom Thalassiosira rotula and assessed the release of PGs in the surrounding environment for the first time. We show that enzymes responsible for PGs formation such as cyclooxygenase, prostaglandin E synthase 2-like and prostaglandin F synthase are mainly expressed at the end of the exponential phase and that PGs are released especially during the stationary and senescent phases, suggesting a possible signaling function for these compounds. Phylogenetic analysis of the limiting enzyme, COX, indicate the presence in diatoms of more than one enzyme related to the oxidative metabolism of fatty acids belonging to the peroxidase-cyclooxygenase superfamily. These findings suggest a more complex evolution and diversity of metabolic pathways leading to the synthesis of lipid mediators in diatoms.
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Affiliation(s)
- Valeria Di Dato
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Napoli, Italy.
| | | | - Alberto Amato
- Laboratoire de Physiologie Cellulaire Végétale, Université Grenoble Alpes, CEA, CNRS, INRA, IRIG-LPCV 38054, Grenoble Cedex 9, France
| | | | - Carolina Fontanarosa
- Dipartimento di Scienze Chimiche, Università degli Studi di Napoli, Monte Sant'Angelo, 80126, Napoli, Italy
| | - Anna Perna
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Napoli, Italy
| | - Angela Amoresano
- Dipartimento di Scienze Chimiche, Università degli Studi di Napoli, Monte Sant'Angelo, 80126, Napoli, Italy
| | | | - Adele Cutignano
- Istituto di Chimica Biomolecolare-CNR, Via Campi Flegrei 34, 80078, Pozzuoli, Napoli, Italy
| | - Adrianna Ianora
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Napoli, Italy
| | - Giovanna Romano
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Napoli, Italy
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Al-Baarri AN, Damayanti NT, Legowo AM, Tekiner İH, Hayakawa S. Enhanced Antibacterial Activity of Lactoperoxidase-Thiocyanate-Hydrogen Peroxide System in Reduced-Lactose Milk Whey. INTERNATIONAL JOURNAL OF FOOD SCIENCE 2019; 2019:8013402. [PMID: 31179314 PMCID: PMC6507251 DOI: 10.1155/2019/8013402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 03/03/2019] [Accepted: 04/03/2019] [Indexed: 11/17/2022]
Abstract
The product of the lactoperoxidase system (LPOS) has been developed as a preservative agent to inhibit foodborne bacteria, but its action was, heretofore, limited to several original compounds in milk. This research was conducted to analyze the application of the lactoperoxidase system against Escherichia coli in fresh bovine milk and its derivative products to determine the strength of antibacterial activity. Lactoperoxidase was purified from bovine whey using the SP Sepharose Big Beads Column. The enzymatic reaction involving lactoperoxidase, thiocyanate, and hydrogen peroxide was used to generate the antibacterial agent from LPOS. This solution was then added to milk, skimmed milk, untreated whey, reduced-LPO whey, reduced-lactose whey, and high-lactose solution containing E. coli at an initial count of 6.0 log CFU/mL. LPOS showed the greatest reduction of bacteria (1.68 ± 0.1 log CFU/mL) in the reduced-lactose whey among the products tested. This result may lead to a method for enhancement of the antimicrobial activity of LPOS in milk and derived products.
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Affiliation(s)
| | - Novia Tri Damayanti
- Animal Sciences Department, Faculty of Animal and Agricultural Sciences, Diponegoro University, Indonesia
| | - Anang Mohamad Legowo
- Animal Sciences Department, Faculty of Animal and Agricultural Sciences, Diponegoro University, Indonesia
| | - İsmail Hakkı Tekiner
- Gastronomy Department, School of Applied Sciences, Istanbul Gelişim University, Turkey
| | - Shigeru Hayakawa
- Applied Biological Sciences, Faculty of Agriculture, Kagawa University, Japan
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Design, Synthesis, Molecular Modeling, and Biological Evaluation of Novel Thiouracil Derivatives as Potential Antithyroid Agents. Molecules 2018; 23:molecules23112913. [PMID: 30413058 PMCID: PMC6278332 DOI: 10.3390/molecules23112913] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/29/2018] [Accepted: 10/30/2018] [Indexed: 12/13/2022] Open
Abstract
Hyperthyroidism is the result of uncontrolled overproduction of the thyroid hormones. One of the mostly used antithyroid agents is 6-n-propyl-2-thiouracil (PTU). The previously solved X-ray crystal structure of the PTU bound to mammalian lactoperoxidase (LPO) reveals that the LPO-PTU binding site is basically a hydrophobic channel. There are two hydrophobic side chains directed towards the oxygen atom in the C-4 position of the thiouracil ring. In the current study, the structural activity relationship (SAR) was performed on the thiouracil nucleus of PTU to target these hydrophobic side chains and gain more favorable interactions and, in return, more antithyroid activity. Most of the designed compounds show superiority over PTU in reducing the mean serum T4 levels of hyperthyroid rats by 3% to 60%. In addition, the effect of these compounds on the levels of serum T3 was found to be comparable to the effect of PTU treatment. The designed compounds in this study showed a promising activity profile in reducing levels of thyroid hormones and follow up experiments will be needed to confirm the use of the designed compounds as new potential antithyroid agents.
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12
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Structural basis of activation of mammalian heme peroxidases. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 133:49-55. [DOI: 10.1016/j.pbiomolbio.2017.11.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 11/14/2017] [Accepted: 11/15/2017] [Indexed: 12/27/2022]
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Sirohi HV, Singh PK, Iqbal N, Sharma P, Singh AK, Kaur P, Sharma S, Singh TP. Design of anti-thyroid drugs: Binding studies and structure determination of the complex of lactoperoxidase with 2-mercaptoimidazole at 2.30 Å resolution. Proteins 2017; 85:1882-1890. [PMID: 28653416 DOI: 10.1002/prot.25342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 06/08/2017] [Accepted: 06/21/2017] [Indexed: 11/08/2022]
Abstract
Lactoperoxidase (LPO) belongs to mammalian heme peroxidase superfamily, which also includes myeloperoxidase (MPO), eosinophil peroxidase (EPO), and thyroid peroxidase (TPO). LPO catalyzes the oxidation of a number of substrates including thiocyanate while TPO catalyzes the biosynthesis of thyroid hormones. LPO is also been shown to catalyze the biosynthesis of thyroid hormones indicating similar functional and structural properties. The binding studies showed that 2-mercaptoimidazole (MZY) bound to LPO with a dissociation constant of 0.63 µM. The inhibition studies showed that the value of IC50 was 17 µM. The crystal structure of the complex of LPO with MZY showed that MZY bound to LPO in the substrate-binding site on the distal heme side. MZY was oriented in the substrate-binding site in such a way that the sulfur atom is at a distance of 2.58 Å from the heme iron. Previously, a similar compound, 3-amino-1,2,4-triazole (amitrole) was also shown to bind to LPO in the substrate-binding site on the distal heme side. The amino nitrogen atom of amitrole occupied the same position as that of sulfur atom in the present structure indicating a similar mode of binding. Recently, the structure of the complex of LPO with a potent antithyroid drug, 1-methylimidazole-2-thiol (methimazole, MMZ) was also determined. It showed that MMZ bound to LPO in the substrate-binding site on the distal heme side with 2 orientations. The position of methyl group was same in the 2 orientations while the positions of sulfur atom differed indicating a higher preference for a methyl group.
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Affiliation(s)
- Harsh V Sirohi
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi
| | - Prashant K Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi
| | - Naseer Iqbal
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi
| | - Pradeep Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi
| | - Amit K Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi
| | - Punit Kaur
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi
| | - Sujata Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi
| | - Tej P Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi
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Yang Y, Zheng N, Zhao X, Zhang Y, Han R, Zhao S, Yang J, Li S, Guo T, Zang C, Wang J. N-glycosylation proteomic characterization and cross-species comparison of milk whey proteins from dairy animals. Proteomics 2017; 17. [DOI: 10.1002/pmic.201600434] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 02/24/2017] [Accepted: 03/02/2017] [Indexed: 01/01/2023]
Affiliation(s)
- Yongxin Yang
- State Key Laboratory of Animal Nutrition; Institute of Animal Sciences; Chinese Academy of Agricultural Sciences; Beijing P. R. China
- Institute of Animal Science and Veterinary Medicine; Anhui Academy of Agricultural Sciences; Hefei China
| | - Nan Zheng
- State Key Laboratory of Animal Nutrition; Institute of Animal Sciences; Chinese Academy of Agricultural Sciences; Beijing P. R. China
| | - Xiaowei Zhao
- State Key Laboratory of Animal Nutrition; Institute of Animal Sciences; Chinese Academy of Agricultural Sciences; Beijing P. R. China
- Institute of Animal Science and Veterinary Medicine; Anhui Academy of Agricultural Sciences; Hefei China
| | - Yangdong Zhang
- State Key Laboratory of Animal Nutrition; Institute of Animal Sciences; Chinese Academy of Agricultural Sciences; Beijing P. R. China
| | - Rongwei Han
- State Key Laboratory of Animal Nutrition; Institute of Animal Sciences; Chinese Academy of Agricultural Sciences; Beijing P. R. China
- College of Food Science and Engineering; Qingdao Agricultural University; Qingdao P. R. China
| | - Shengguo Zhao
- State Key Laboratory of Animal Nutrition; Institute of Animal Sciences; Chinese Academy of Agricultural Sciences; Beijing P. R. China
| | - Jinhui Yang
- State Key Laboratory of Animal Nutrition; Institute of Animal Sciences; Chinese Academy of Agricultural Sciences; Beijing P. R. China
| | - Songli Li
- State Key Laboratory of Animal Nutrition; Institute of Animal Sciences; Chinese Academy of Agricultural Sciences; Beijing P. R. China
| | - Tongjun Guo
- State Key Laboratory of Animal Nutrition; Institute of Animal Sciences; Chinese Academy of Agricultural Sciences; Beijing P. R. China
| | - Changjiang Zang
- State Key Laboratory of Animal Nutrition; Institute of Animal Sciences; Chinese Academy of Agricultural Sciences; Beijing P. R. China
| | - Jiaqi Wang
- State Key Laboratory of Animal Nutrition; Institute of Animal Sciences; Chinese Academy of Agricultural Sciences; Beijing P. R. China
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15
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Singh PK, Sirohi HV, Iqbal N, Tiwari P, Kaur P, Sharma S, Singh TP. Structure of bovine lactoperoxidase with a partially linked heme moiety at 1.98Å resolution. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:329-335. [DOI: 10.1016/j.bbapap.2016.12.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 12/05/2016] [Accepted: 12/10/2016] [Indexed: 11/26/2022]
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16
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Köksal Z, Usanmaz H, Bayrak S, Ozdemir H. Improved chromatographic method for purification of lactoperoxidase from different milk sources. Prep Biochem Biotechnol 2016; 47:129-136. [DOI: 10.1080/10826068.2016.1185732] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Zeynep Köksal
- Department of Chemistry, Faculty of Sciences, Atatürk University, Erzurum, Turkey
- Department of Chemistry, Faculty of Sciences, Istanbul Medeniyet University, Istanbul, Turkey
| | - Hande Usanmaz
- Department of Bioengineering, Faculty of Engineering and Architecture, Sinop University, Sinop, Turkey
| | - Songül Bayrak
- Department of Chemistry, Faculty of Sciences, Atatürk University, Erzurum, Turkey
| | - Hasan Ozdemir
- Department of Chemistry, Faculty of Sciences, Atatürk University, Erzurum, Turkey
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17
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Gau J, Furtmüller PG, Obinger C, Prévost M, Van Antwerpen P, Arnhold J, Flemmig J. Flavonoids as promoters of the (pseudo-)halogenating activity of lactoperoxidase and myeloperoxidase. Free Radic Biol Med 2016; 97:307-319. [PMID: 27350402 DOI: 10.1016/j.freeradbiomed.2016.06.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/23/2016] [Accepted: 06/23/2016] [Indexed: 01/05/2023]
Abstract
In this study several flavonoids were tested for their potential to regenerate the (pseudo-)halogenating activity (hypothiocyanite formation) of the heme peroxidases lactoperoxidase (LPO) and myeloperoxidase (MPO) after hydrogen peroxide-mediated enzyme inactivation. Several flavonoid subclasses with varying hydroxylation patterns (especially of the flavonoid B-ring) were examined in order to identify structural properties of efficient enzyme regenerators. Kinetic parameters and second-order rate constants were determined. A 3',4'-dihydroxylated B-ring together with C-ring saturation and hydroxylation were found to be important structural elements, which strongly influence the flavonoid binding and oxidizability by the LPO/MPO redox intermediates Compounds I and II. In combination with docking studies these results allow an understanding of the differences between flavonoids that promote the hypothiocyanite production by LPO and MPO and those that inhibit this enzymatic reaction.
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Affiliation(s)
- Jana Gau
- Institute for Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany.
| | - Paul G Furtmüller
- Department of Chemistry, Division of Biochemistry, University of Natural Resources and Life Sciences (BOKU) Vienna, Muthgasse 18, 1190 Vienna, Austria.
| | - Christian Obinger
- Department of Chemistry, Division of Biochemistry, University of Natural Resources and Life Sciences (BOKU) Vienna, Muthgasse 18, 1190 Vienna, Austria.
| | - Martine Prévost
- Laboratory of Structure and Function of Biological Membranes, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Brussels, Belgium.
| | - Pierre Van Antwerpen
- Laboratory of Pharmaceutical Organic Chemistry, Institute of Pharmacy, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Brussels, Belgium.
| | - Jürgen Arnhold
- Institute for Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany.
| | - Jörg Flemmig
- Institute for Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany.
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18
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Singh RP, Singh A, Sirohi HV, Singh AK, Kaur P, Sharma S, Singh TP. Dual binding mode of antithyroid drug methimazole to mammalian heme peroxidases - structural determination of the lactoperoxidase-methimazole complex at 1.97 Å resolution. FEBS Open Bio 2016; 6:640-50. [PMID: 27398304 PMCID: PMC4932444 DOI: 10.1002/2211-5463.12051] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/27/2016] [Accepted: 02/29/2016] [Indexed: 11/09/2022] Open
Abstract
Lactoperoxidase (LPO, EC 1.11.1.7) is a member of the mammalian heme peroxidase family which also includes thyroid peroxidase (TPO). These two enzymes have a sequence homology of 76%. The structure of LPO is known but not that of TPO. In order to determine the mode of binding of antithyroid drugs to thyroid peroxidase, we have determined the crystal structure of LPO complexed with an antithyroid drug, methimazole (MMZ) at 1.97 Å resolution. LPO was isolated from caprine colostrum, purified to homogeneity and crystallized with 20% poly(ethylene glycol)‐3350. Crystals of LPO were soaked in a reservoir solution containing MMZ. The structure determination showed the presence of two crystallographically independent molecules in the asymmetric unit. Both molecules contained one molecule of MMZ, but with different orientations. MMZ was held tightly between the heme moiety on one side and the hydrophobic parts of the side chains of Arg255, Glu258, and Leu262 on the opposite side. The back of the cleft contained the side chains of Gln105 and His109 which also interacted with MMZ. In both orientations, MMZ had identical buried areas and formed a similar number of interactions. It appears that the molecules of MMZ can enter the substrate‐binding channel of LPO in two opposite orientations. But once they reach the distal heme pocket, their orientations are frozen due to equally tight packing of MMZ in both orientations. This is a novel example of an inhibitor binding to an enzyme with two orientations at the same site with nearly equal occupancies.
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Affiliation(s)
- Rashmi Prabha Singh
- Department of Biophysics All India Institute of Medical Sciences New Delhi India
| | - Avinash Singh
- Department of Biophysics All India Institute of Medical Sciences New Delhi India
| | - Harsh Vardhan Sirohi
- Department of Biophysics All India Institute of Medical Sciences New Delhi India
| | - Amit Kumar Singh
- Department of Biophysics All India Institute of Medical Sciences New Delhi India
| | - Punit Kaur
- Department of Biophysics All India Institute of Medical Sciences New Delhi India
| | - Sujata Sharma
- Department of Biophysics All India Institute of Medical Sciences New Delhi India
| | - Tej P Singh
- Department of Biophysics All India Institute of Medical Sciences New Delhi India
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19
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T47D Cells Expressing Myeloperoxidase Are Able to Process, Traffic and Store the Mature Protein in Lysosomes: Studies in T47D Cells Reveal a Role for Cys319 in MPO Biosynthesis that Precedes Its Known Role in Inter-Molecular Disulfide Bond Formation. PLoS One 2016; 11:e0149391. [PMID: 26890638 PMCID: PMC4758715 DOI: 10.1371/journal.pone.0149391] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 02/01/2016] [Indexed: 01/10/2023] Open
Abstract
Among the human heme-peroxidase family, myeloperoxidase (MPO) has a unique disulfide-linked oligomeric structure resulting from multi-step processing of the pro-protein monomer (proMPO) after it exits the endoplasmic reticulum (ER). Related family members undergo some, but not all, of the processing steps involved with formation of mature MPO. Lactoperoxidase has its pro-domain proteolytically removed and is a monomer in its mature form. Eosinophil peroxidase undergoes proteolytic removal of its pro-domain followed by proteolytic separation into heavy and light chains and is a heterodimer. However, only MPO undergoes both these proteolytic modifications and then is further oligomerized into a heterotetramer by a single inter-molecular disulfide bond. The details of how and where the post-ER processing steps of MPO occur are incompletely understood. We report here that T47D breast cancer cells stably transfected with an MPO expression plasmid are able to efficiently replicate all of the processing steps that lead to formation of the mature MPO heterotetramer. MPO also traffics to the lysosome granules of T47D cells where it accumulates, allowing in-depth immunofluorescent microscopy studies of MPO trafficking and storage for the first time. Using this novel cell model we show that formation of MPO’s single inter-molecular disulfide bond can occur normally in the absence of the proteolytic events that lead to separation of the MPO heavy and light chains. We further demonstrate that Cys319, which forms MPO’s unique inter-molecular disulfide bond, is important for events that precede this step. Mutation of this residue alters the glycosylation and catalytic activity of MPO and blocks its entry into the endocytic pathway where proteolytic processing and disulfide bonding occur. Finally, using the endocytic trafficking of lysosomal hydrolases as a guide, we investigate the role of candidate receptors in the endocytic trafficking of MPO.
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20
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Flemmig J, Gau J, Schlorke D, Arnhold J. Lactoperoxidase as a potential drug target. Expert Opin Ther Targets 2015; 20:447-61. [DOI: 10.1517/14728222.2016.1112378] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jörg Flemmig
- Institute for Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Härtelstraße 16 – 18, 04107 Leipzig, Germany
- Translational Centre for Regenerative Medicine (TRM) Leipzig, University of Leipzig, Leipzig, Germany
| | - Jana Gau
- Institute for Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Härtelstraße 16 – 18, 04107 Leipzig, Germany
| | - Denise Schlorke
- Institute for Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Härtelstraße 16 – 18, 04107 Leipzig, Germany
- Translational Centre for Regenerative Medicine (TRM) Leipzig, University of Leipzig, Leipzig, Germany
| | - Jürgen Arnhold
- Institute for Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Härtelstraße 16 – 18, 04107 Leipzig, Germany
- Translational Centre for Regenerative Medicine (TRM) Leipzig, University of Leipzig, Leipzig, Germany
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21
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Iwaoka M, Babe N. Mining and Structural Characterization of S···X Chalcogen Bonds in Protein Database. PHOSPHORUS SULFUR 2015. [DOI: 10.1080/10426507.2014.1002612] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Michio Iwaoka
- Department of Chemistry, School of Science, Tokai University, Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan
| | - Natsuki Babe
- Department of Chemistry, School of Science, Tokai University, Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan
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22
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99mTc-amitrole as a novel selective imaging probe for solid tumor: In silico and preclinical pharmacological study. Eur J Pharm Sci 2015; 76:102-9. [DOI: 10.1016/j.ejps.2015.05.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 04/23/2015] [Accepted: 05/03/2015] [Indexed: 11/17/2022]
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23
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Lázár E, Péterfi Z, Sirokmány G, Kovács HA, Klement E, Medzihradszky KF, Geiszt M. Structure-function analysis of peroxidasin provides insight into the mechanism of collagen IV crosslinking. Free Radic Biol Med 2015; 83:273-82. [PMID: 25708780 DOI: 10.1016/j.freeradbiomed.2015.02.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 02/07/2015] [Accepted: 02/11/2015] [Indexed: 11/21/2022]
Abstract
Basement membranes provide structural support and convey regulatory signals to cells in diverse tissues. Assembly of collagen IV into a sheet-like network is a fundamental mechanism during the formation of basement membranes. Peroxidasin (PXDN) was recently described to catalyze crosslinking of collagen IV through the formation of sulfilimine bonds. Despite the significance of this pathway in tissue genesis, our understanding of PXDN function is far from complete. In this work we demonstrate that collagen IV crosslinking is a physiological function of mammalian PXDN. Moreover, we carried out structure-function analysis of PXDN to gain a better insight into its role in collagen IV synthesis. We identify conserved cysteines in PXDN that mediate the oligomerization of the protein into a trimeric complex. We also demonstrate that oligomerization is not an absolute requirement for enzymatic activity, but optimal collagen IV coupling is only catalyzed by the PXDN trimers. Localization experiments of different PXDN mutants in two different cell models revealed that PXDN oligomers, but not monomers, adhere on the cell surface in "hot spots," which represent previously unknown locations of collagen IV crosslinking.
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MESH Headings
- Animals
- Antigens, Neoplasm/chemistry
- Antigens, Neoplasm/genetics
- Antigens, Neoplasm/metabolism
- Apoptosis
- Basement Membrane/metabolism
- Blotting, Western
- Catalysis
- Cell Proliferation
- Cells, Cultured
- Collagen Type IV/chemistry
- Collagen Type IV/metabolism
- Cross-Linking Reagents/pharmacology
- Extracellular Matrix/metabolism
- Extracellular Matrix Proteins/physiology
- Female
- Fluorescent Antibody Technique
- Humans
- Immunoenzyme Techniques
- Immunoprecipitation
- Mice
- Mice, Knockout
- Peroxidase/physiology
- Peroxidases
- Protein Conformation
- RNA, Messenger/genetics
- Real-Time Polymerase Chain Reaction
- Receptors, Interleukin-1/chemistry
- Receptors, Interleukin-1/genetics
- Receptors, Interleukin-1/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Structure-Activity Relationship
- Peroxidasin
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Affiliation(s)
- Enikő Lázár
- Department of Physiology, Semmelweis University, Budapest, Hungary; "Momentum" Peroxidase Enzyme Research Group of the Semmelweis University and the Hungarian Academy of Sciences, Szeged, Hungary
| | - Zalán Péterfi
- Department of Physiology, Semmelweis University, Budapest, Hungary; "Momentum" Peroxidase Enzyme Research Group of the Semmelweis University and the Hungarian Academy of Sciences, Szeged, Hungary
| | - Gábor Sirokmány
- Department of Physiology, Semmelweis University, Budapest, Hungary; "Momentum" Peroxidase Enzyme Research Group of the Semmelweis University and the Hungarian Academy of Sciences, Szeged, Hungary
| | - Hajnal A Kovács
- Department of Physiology, Semmelweis University, Budapest, Hungary; "Momentum" Peroxidase Enzyme Research Group of the Semmelweis University and the Hungarian Academy of Sciences, Szeged, Hungary
| | - Eva Klement
- Laboratory of Proteomics Research, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Katalin F Medzihradszky
- Laboratory of Proteomics Research, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary; Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | - Miklós Geiszt
- Department of Physiology, Semmelweis University, Budapest, Hungary; "Momentum" Peroxidase Enzyme Research Group of the Semmelweis University and the Hungarian Academy of Sciences, Szeged, Hungary.
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24
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Singh RP, Singh A, Kushwaha GS, Singh AK, Kaur P, Sharma S, Singh TP. Mode of binding of the antithyroid drug propylthiouracil to mammalian haem peroxidases. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2015; 71:304-10. [PMID: 25760705 DOI: 10.1107/s2053230x15001806] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 01/27/2015] [Indexed: 11/10/2022]
Abstract
The mammalian haem peroxidase superfamily consists of myeloperoxidase (MPO), lactoperoxidase (LPO), eosinophil peroxidase (EPO) and thyroid peroxidase (TPO). These enzymes catalyze a number of oxidative reactions of inorganic substrates such as Cl(-), Br(-), I(-) and SCN(-) as well as of various organic aromatic compounds. To date, only structures of MPO and LPO are known. The substrate-binding sites in these enzymes are located on the distal haem side. Propylthiouracil (PTU) is a potent antithyroid drug that acts by inhibiting the function of TPO. It has also been shown to inhibit the action of LPO. However, its mode of binding to mammalian haem peroxidases is not yet known. In order to determine the mode of its binding to peroxidases, the structure of the complex of LPO with PTU has been determined. It showed that PTU binds to LPO in the substrate-binding site on the distal haem side. The IC50 values for the inhibition of LPO and TPO by PTU are 47 and 30 µM, respectively. A comparision of the residues surrounding the substrate-binding site on the distal haem side in LPO with those in TPO showed that all of the residues were identical except for Ala114 (LPO numbering scheme), which is replaced by Thr205 (TPO numbering scheme) in TPO. A threonine residue in place of alanine in the substrate-binding site may affect the affinity of PTU for peroxidases.
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Affiliation(s)
- R P Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - A Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - G S Kushwaha
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - A K Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - P Kaur
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - S Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - T P Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
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25
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Mak PJ, Thammawichai W, Wiedenhoeft D, Kincaid JR. Resonance Raman Spectroscopy Reveals pH-Dependent Active Site Structural Changes of Lactoperoxidase Compound 0 and Its Ferryl Heme O–O Bond Cleavage Products. J Am Chem Soc 2014; 137:349-61. [DOI: 10.1021/ja5107833] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Piotr J. Mak
- Department
of Chemistry, Marquette University, Milwaukee, Wisconsin 53233, United States
| | - Warut Thammawichai
- Department
of Chemistry, Marquette University, Milwaukee, Wisconsin 53233, United States
| | - Dennis Wiedenhoeft
- Department
of Chemistry, Marquette University, Milwaukee, Wisconsin 53233, United States
| | - James R. Kincaid
- Department
of Chemistry, Marquette University, Milwaukee, Wisconsin 53233, United States
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26
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Sharma S, Singh AK, Kaushik S, Sinha M, Singh RP, Sharma P, Sirohi H, Kaur P, Singh TP. Lactoperoxidase: structural insights into the function,ligand binding and inhibition. INTERNATIONAL JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 4:108-128. [PMID: 24049667 PMCID: PMC3776144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 08/21/2013] [Indexed: 06/02/2023]
Abstract
Lactoperoxidase (LPO) is a member of a large group of mammalian heme peroxidases that include myeloperoxidase (MPO), eosinophil peroxidase (EPO) and thyroid peroxidase (TPO). The LPO is found in exocrine secretions including milk. It is responsible for the inactivation of a wide range of micro-organisms and hence, is an important component of defense mechanism in the body. With the help of hydrogen peroxide, it catalyzes the oxidation of halides, pseudohalides and organic aromatic molecules. Historically, LPO was isolated in 1943, nearly seventy years ago but its three-dimensional crystal structure has been elucidated only recently. This review provides various details of this protein from its discovery to understanding its structure, function and applications. In order to highlight species dependent variations in the structure and function of LPO, a detailed comparison of sequence, structure and function of LPO from various species have been made. The structural basis of ligand binding and distinctions in the modes of binding of substrates and inhibitors have been analyzed extensively.
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Affiliation(s)
- Sujata Sharma
- Department of Biophysics, All India Institute of Medical Sciences New Delhi - 110029, India
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27
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Auer M, Gruber C, Bellei M, Pirker KF, Zamocky M, Kroiss D, Teufer SA, Hofbauer S, Soudi M, Battistuzzi G, Furtmüller PG, Obinger C. A stable bacterial peroxidase with novel halogenating activity and an autocatalytically linked heme prosthetic group. J Biol Chem 2013; 288:27181-27199. [PMID: 23918925 DOI: 10.1074/jbc.m113.477067] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Reconstructing the phylogenetic relationships of the main evolutionary lines of the mammalian peroxidases lactoperoxidase and myeloperoxidase revealed the presence of novel bacterial heme peroxidase subfamilies. Here, for the first time, an ancestral bacterial heme peroxidase is shown to possess a very high bromide oxidation activity (besides conventional peroxidase activity). The recombinant protein allowed monitoring of the autocatalytic peroxide-driven formation of covalent heme to protein bonds. Thereby, the high spin ferric rhombic heme spectrum became similar to lactoperoxidase, the standard reduction potential of the Fe(III)/Fe(II) couple shifted to more positive values (-145 ± 10 mV at pH 7), and the conformational and thermal stability of the protein increased significantly. We discuss structure-function relationships of this new peroxidase in relation to its mammalian counterparts and ask for its putative physiological role.
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Affiliation(s)
- Markus Auer
- Division of Biochemistry, Department of Chemistry, Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Clemens Gruber
- Division of Biochemistry, Department of Chemistry, Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | | | - Katharina F Pirker
- Division of Biochemistry, Department of Chemistry, Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Marcel Zamocky
- Division of Biochemistry, Department of Chemistry, Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria; Institute of Molecular Biology, Slovak Academy of Sciences, 84551 Bratislava, Slovakia
| | - Daniela Kroiss
- Division of Biochemistry, Department of Chemistry, Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Stefan A Teufer
- Division of Biochemistry, Department of Chemistry, Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Stefan Hofbauer
- Division of Biochemistry, Department of Chemistry, Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Monika Soudi
- Division of Biochemistry, Department of Chemistry, Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Gianantonio Battistuzzi
- Departments of Chemistry and Geology, University of Modena and Reggio Emilia, 41100 Modena, Italy
| | - Paul G Furtmüller
- Division of Biochemistry, Department of Chemistry, Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Christian Obinger
- Division of Biochemistry, Department of Chemistry, Vienna Institute of BioTechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
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28
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Bovine Carbonyl Lactoperoxidase Structure at 2.0Å Resolution and Infrared Spectra as a Function of pH. Protein J 2012; 31:598-608. [DOI: 10.1007/s10930-012-9436-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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29
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Chandler JD, Day BJ. Thiocyanate: a potentially useful therapeutic agent with host defense and antioxidant properties. Biochem Pharmacol 2012; 84:1381-7. [PMID: 22968041 DOI: 10.1016/j.bcp.2012.07.029] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 07/26/2012] [Accepted: 07/26/2012] [Indexed: 12/15/2022]
Abstract
Thiocyanate (SCN) functions in host defense as part of the secreted lactoperoxidase (LPO) microbicidal pathway. SCN is the preferred substrate for LPO-driven catalytic reduction of hydrogen peroxide (H(2)O(2)) forming hypothiocyanous acid (HOSCN). HOSCN is selectively generated by many peroxidase enzymes that can utilize SCN including: eosinophil peroxidase (EPO), gastric peroxidase (GPO), myeloperoxidase (MPO), salivary peroxidase (SPO), and thyroid peroxidase (TPO). These enzymes generate HOSCN through a two-electron halogenation reaction. HOSCN is a potent microbicidal agent that kills or nullifies invading pathogens but is better tolerated by host tissue. Some controversy exists as to whether physiologic levels of HOSCN are non-toxic to host tissue, but the disagreement appears to be based on results of enzymatic generation (yielding moderate steady-state exposure) versus direct high level acute exposure in mammalian cell lines. This apparent duality is also true of other endogenous oxidants such as hydrogen peroxide and relates to the difference between physiologically relevant oxidant production versus supra-physiologic bolus dosing approaches. SCN has antioxidant properties that include the ability to protect cells against oxidizing agents such as hypochlorous acid (HOCl) and repair protein chloramines. SCN is an important endogenous molecule that has the potential to interact in complex and elegant ways with its host environment and foreign organisms. SCN's diverse properties as both host defense and antioxidant agent make it a potentially useful therapeutic.
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Affiliation(s)
- Joshua D Chandler
- Department of Medicine, National Jewish Health, Denver, CO 80206, United States
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Iwaoka M, Isozumi N. Hypervalent nonbonded interactions of a divalent sulfur atom. Implications in protein architecture and the functions. Molecules 2012; 17:7266-83. [PMID: 22695232 PMCID: PMC6269016 DOI: 10.3390/molecules17067266] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 06/06/2012] [Accepted: 06/08/2012] [Indexed: 12/30/2022] Open
Abstract
In organic molecules a divalent sulfur atom sometimes adopts weak coordination to a proximate heteroatom (X). Such hypervalent nonbonded S···X interactions can control the molecular structure and chemical reactivity of organic molecules, as well as their assembly and packing in the solid state. In the last decade, similar hypervalent interactions have been demonstrated by statistical database analysis to be present in protein structures. In this review, weak interactions between a divalent sulfur atom and an oxygen or nitrogen atom in proteins are highlighted with several examples. S···O interactions in proteins showed obviously different structural features from those in organic molecules (i.e., π(o) → σ(s)* versus n(o) → σ(s)* directionality). The difference was ascribed to the HOMO of the amide group, which expands in the vertical direction (π(o)) rather than in the plane (n(o)). S···X interactions in four model proteins, phospholipase A₂ (PLA₂), ribonuclease A (RNase A), insulin, and lysozyme, have also been analyzed. The results suggested that S···X interactions would be important factors that control not only the three-dimensional structure of proteins but also their functions to some extent. Thus, S···X interactions will be useful tools for protein engineering and the ligand design.
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Affiliation(s)
- Michio Iwaoka
- Department of Chemistry, School of Science, Tokai University, Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan.
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31
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Murphy EJ, Metcalfe CL, Nnamchi C, Moody PCE, Raven EL. Crystal structure of guaiacol and phenol bound to a heme peroxidase. FEBS J 2011; 279:1632-9. [PMID: 22093282 DOI: 10.1111/j.1742-4658.2011.08425.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Guaiacol is a universal substrate for all peroxidases, and its use in a simple colorimetric assay has wide applications. However, its exact binding location has never been defined. Here we report the crystal structures of guaiacol bound to cytochrome c peroxidase (CcP). A related structure with phenol bound is also presented. The CcP-guaiacol and CcP-phenol crystal structures show that both guaiacol and phenol bind at sites distinct from the cytochrome c binding site and from the δ-heme edge, which is known to be the binding site for other substrates. Although neither guaiacol nor phenol is seen bound at the δ-heme edge in the crystal structures, inhibition data and mutagenesis strongly suggest that the catalytic binding site for aromatic compounds is the δ-heme edge in CcP. The functional implications of these observations are discussed in terms of our existing understanding of substrate binding in peroxidases [Gumiero A et al. (2010) Arch Biochem Biophys 500, 13-20].
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Affiliation(s)
- Emma J Murphy
- Department of Chemistry, University of Leicester, Leicester, UK
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Singh AK, Pandey N, Sinha M, Kaur P, Sharma S, Singh TP. Structural evidence for the order of preference of inorganic substrates in mammalian heme peroxidases: crystal structure of the complex of lactoperoxidase with four inorganic substrates, SCN, I, Br and Cl. INTERNATIONAL JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2011; 2:328-339. [PMID: 22187667 PMCID: PMC3242431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 11/12/2011] [Indexed: 05/31/2023]
Abstract
Lactoperoxidase (LPO) is a member of the family of mammalian heme peroxidases. It catalyzes the oxidation of halides and pseudohalides in presence of hydrogen peroxide. LPO has been co-crystallized with inorganic substrates, SCN(-), I(-), Br(-) and Cl(-). The structure determination of the complex of LPO with above four substrates showed that all of them occupied distinct positions in the substrate binding site on the distal heme side. The bound substrate ions were separated from each other by one or more water molecules. The heme iron is coordinated to His-351 N(ϵ2) on the proximal side while it is coordinated to conserved water molecule W-1 on the distal heme side. W-1 is hydrogen bonded to Br(-) ion which is followed by Cl(-) ion with a hydrogen bonded water molecule W-5' between them. Next to Cl(-) ion is a hydrogen bonded water molecule W-7' which in turn is hydrogen bonded to W-8' and N atom of SCN(-). W-80 is hydrogen bonded to W-9' which is hydrogen bonded to I(-). SCN(-) ion also interacts directly with Asn-230 and through water molecules with Ser-235 and Phe-254. Therefore, according to the locations of four substrate anions, the order of preference for binding to lactoperoxidase is observed as Br(-) > Cl(-) > SCN(-) > I(-). The positions of anions are further defined in terms of subsites where Br(-) is located in subsite 1, Cl(-) in subsite 2, SCN(-) in subsite 3 and I(-) in subsite 4.
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Affiliation(s)
- Amit K Singh
- Department of Biophysics, All India Institute of Medical Sciences New Delhi India
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Al-Baarri AN, Hayashi M, Ogawa M, Hayakawa S. Effects of mono- and disaccharides on the antimicrobial activity of bovine lactoperoxidase system. J Food Prot 2011; 74:134-9. [PMID: 21219776 DOI: 10.4315/0362-028x.jfp-10-184] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The effects of mono- and disaccharides on the antimicrobial activity of the lactoperoxidase (LPO) system against Salmonella Enteritidis were investigated. The results clearly reveal that most of the sugars inhibit the antimicrobial activity of the LPO system. The inhibitory potency varies depending on the structure of sugar. L-Fructose and D-allose were strongly inhibitive to the action of the LPO system, while sucrose was the weakest inhibitor. The decreased antimicrobial activity is due to the reduction of LPO catalytic activity by sugar. An inhibitory kinetic study showed the noncompetitive inhibitor. D-Allose and L-fructose yielded strikingly low K(i) values of 0.36 and 0.42 mM, respectively, while the K(i) values of the other sugars ranged from 1.37 to 3.60 mM. Since LPO activity is inhibited by the saccharides, the sugar content in food should be considered when the LPO system is applied to the preservation of food.
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Affiliation(s)
- Ahmad Nimatullah Al-Baarri
- Department of Applied Biological Sciences, Kagawa University, 2393, Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0795, Japan
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34
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Gumiero A, Murphy EJ, Metcalfe CL, Moody PC, Raven EL. An analysis of substrate binding interactions in the heme peroxidase enzymes: A structural perspective. Arch Biochem Biophys 2010; 500:13-20. [DOI: 10.1016/j.abb.2010.02.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 02/23/2010] [Accepted: 02/27/2010] [Indexed: 11/29/2022]
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Murphy EJ, Maréchal A, Segal AW, Rich PR. CO binding and ligand discrimination in human myeloperoxidase. Biochemistry 2010; 49:2150-8. [PMID: 20146436 DOI: 10.1021/bi9021507] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Despite the fact that ferrous myeloperoxidase (MPO) can bind both O(2) and NO, its ability to bind CO has been questioned. UV/visible spectroscopy was used to confirm that CO induces small spectral shifts in ferrous MPO, and Fourier transform infrared difference spectroscopy showed definitively that these arose from formation of a heme ferrous-CO compound. Recombination rates after CO photolysis were monitored at 618 and 645 nm as a function of CO concentration and pH. At pH 6.3, k(on) and k(off) were 0.14 mM(-1) x s(-1) and 0.23 s(-1), respectively, yielding an unusually high K(D) of 1.6 mM. This affinity of MPO for CO is 10 times weaker than its affinity for O(2). The observed rate constant for CO binding increased with increasing pH and was governed by a single protonatable group with a pK(a) of 7.8. Fourier transform infrared spectroscopy revealed two different conformations of bound CO with frequencies at 1927 and 1942 cm(-1). Their recombination rate constants were identical, indicative of two forms of bound CO that are in rapid thermal equilibrium rather than two distinct protein populations with different binding sites. The ratio of bound states was pH-dependent (pK(a) approximately 7.4) with the 1927 cm(-1) form favored at high pH. Structural factors that account for the ligand-binding properties of MPO are identified by comparisons with published data on a range of other ligand-binding heme proteins, and support is given to the recent suggestion that the proximal His336 in MPO is in a true imidazolate state.
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Affiliation(s)
- Emma J Murphy
- Centre for Molecular Medicine, Division of Medicine, University College London, 5 University Street, London WC1E 6JJ, UK
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Toyama A, Tominaga A, Inoue T, Takeuchi H. Activation of lactoperoxidase by heme-linked protonation and heme-independent iodide binding. Biopolymers 2010; 93:113-20. [DOI: 10.1002/bip.21308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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37
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Singh AK, Kumar RP, Pandey N, Singh N, Sinha M, Bhushan A, Kaur P, Sharma S, Singh TP. Mode of binding of the tuberculosis prodrug isoniazid to heme peroxidases: binding studies and crystal structure of bovine lactoperoxidase with isoniazid at 2.7 A resolution. J Biol Chem 2009; 285:1569-76. [PMID: 19907057 DOI: 10.1074/jbc.m109.060327] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Isoniazid (INH) is an anti-tuberculosis prodrug that is activated by mammalian lactoperoxidase and Mycobacterium tuberculosis catalase peroxidase (MtCP). We report here binding studies, an enzyme assay involving INH, and the crystal structure of the complex of bovine lactoperoxidase (LPO) with INH to illuminate binding properties and INH activation as well as the mode of diffusion and interactions together with a detailed structural and functional comparison with MtCP. The structure determination shows that isoniazid binds to LPO at the substrate binding site on the distal heme side. The substrate binding site is connected to the protein surface through a long hydrophobic channel. The acyl hydrazide moiety of isoniazid interacts with Phe(422) O, Gln(423) O(epsilon1), and Phe(254) O. In this arrangement, pyridinyl nitrogen forms a hydrogen bond with a water molecule, W-1, which in turn forms three hydrogen bonds with Fe(3+), His(109) N(epsilon2), and Gln(105) N(epsilon2). The remaining two sides of isoniazid form hydrophobic interactions with the atoms of heme pyrrole ring A, C(beta) and C(gamma) atoms of Glu(258), and C(gamma) and C(delta) atoms of Arg(255). The binding studies indicate that INH binds to LPO with a value of 0.9 x 10(-6) m for the dissociation constant. The nitro blue tetrazolium reduction assay shows that INH is activated by the reaction of LPO-H(2)O(2) with INH. This suggests that LPO can be used for INH activation. It also indicates that the conversion of INH into isonicotinoyl radical by LPO may be the cause of INH toxicity.
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Affiliation(s)
- Amit K Singh
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029, India
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Singh AK, Singh N, Sinha M, Bhushan A, Kaur P, Srinivasan A, Sharma S, Singh TP. Binding modes of aromatic ligands to mammalian heme peroxidases with associated functional implications: crystal structures of lactoperoxidase complexes with acetylsalicylic acid, salicylhydroxamic acid, and benzylhydroxamic acid. J Biol Chem 2009; 284:20311-8. [PMID: 19465478 PMCID: PMC2740456 DOI: 10.1074/jbc.m109.010280] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Indexed: 11/06/2022] Open
Abstract
The binding and structural studies of bovine lactoperoxidase with three aromatic ligands, acetylsalicylic acid (ASA), salicylhydoxamic acid (SHA), and benzylhydroxamic acid (BHA) show that all the three compounds bind to lactoperoxidase at the substrate binding site on the distal heme side. The binding of ASA occurs without perturbing the position of conserved heme water molecule W-1, whereas both SHA and BHA displace it by the hydroxyl group of their hydroxamic acid moieties. The acetyl group carbonyl oxygen atom of ASA forms a hydrogen bond with W-1, which in turn makes three other hydrogen-bonds, one each with heme iron, His-109 N(epsilon2), and Gln-105 N(epsilon2). In contrast, in the complexes of SHA and BHA, the OH group of hydroxamic acid moiety in both complexes interacts with heme iron directly with Fe-OH distances of 3.0 and 3.2A respectively. The OH is also hydrogen bonded to His-109 N(epsilon2) and Gln-105N(epsilon2). The plane of benzene ring of ASA is inclined at 70.7 degrees from the plane of heme moiety, whereas the aromatic planes of SHA and BHA are nearly parallel to the heme plane with inclinations of 15.7 and 6.2 degrees , respectively. The mode of ASA binding provides the information about the mechanism of action of aromatic substrates, whereas the binding characteristics of SHA and BHA indicate the mode of inhibitor binding.
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Affiliation(s)
- Amit K. Singh
- From the Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
| | - Nagendra Singh
- From the Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
| | - Mau Sinha
- From the Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
| | - Asha Bhushan
- From the Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
| | - Punit Kaur
- From the Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
| | - Alagiri Srinivasan
- From the Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
| | - Sujata Sharma
- From the Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
| | - Tej P. Singh
- From the Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
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Sheikh IA, Singh AK, Singh N, Sinha M, Singh SB, Bhushan A, Kaur P, Srinivasan A, Sharma S, Singh TP. Structural evidence of substrate specificity in mammalian peroxidases: structure of the thiocyanate complex with lactoperoxidase and its interactions at 2.4 A resolution. J Biol Chem 2009; 284:14849-56. [PMID: 19339248 PMCID: PMC2685666 DOI: 10.1074/jbc.m807644200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 03/18/2009] [Indexed: 11/06/2022] Open
Abstract
The crystal structure of the complex of lactoperoxidase (LPO) with its physiological substrate thiocyanate (SCN(-)) has been determined at 2.4A resolution. It revealed that the SCN(-) ion is bound to LPO in the distal heme cavity. The observed orientation of the SCN(-) ion shows that the sulfur atom is closer to the heme iron than the nitrogen atom. The nitrogen atom of SCN(-) forms a hydrogen bond with a water (Wat) molecule at position 6'. This water molecule is stabilized by two hydrogen bonds with Gln(423) N(epsilon2) and Phe(422) oxygen. In contrast, the placement of the SCN(-) ion in the structure of myeloperoxidase (MPO) occurs with an opposite orientation, in which the nitrogen atom is closer to the heme iron than the sulfur atom. The site corresponding to the positions of Gln(423), Phe(422) oxygen, and Wat(6)' in LPO is occupied primarily by the side chain of Phe(407) in MPO due to an entirely different conformation of the loop corresponding to the segment Arg(418)-Phe(431) of LPO. This arrangement in MPO does not favor a similar orientation of the SCN(-) ion. The orientation of the catalytic product OSCN(-) as reported in the structure of LPO.OSCN(-) is similar to the orientation of SCN(-) in the structure of LPO.SCN(-). Similarly, in the structure of LPO.SCN(-).CN(-), in which CN(-) binds at Wat(1), the position and orientation of the SCN(-) ion are also identical to that observed in the structure of LPO.SCN.
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Affiliation(s)
- Ishfaq Ahmed Sheikh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
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