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Jittavisutthikul S, Seesuay W, Thanongsaksrikul J, Thueng-in K, Srimanote P, Werner RG, Chaicumpa W. Human Transbodies to HCV NS3/4A Protease Inhibit Viral Replication and Restore Host Innate Immunity. Front Immunol 2016; 7:318. [PMID: 27617013 PMCID: PMC4999588 DOI: 10.3389/fimmu.2016.00318] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 08/08/2016] [Indexed: 12/23/2022] Open
Abstract
A safe and effective direct acting anti-hepatitis C virus (HCV) agent is still needed. In this study, human single chain variable fragments of antibody (scFvs) that bound to HCV NS3/4A protein were produced by phage display technology. The engineered scFvs were linked to nonaarginines (R9) for making them cell penetrable. HCV-RNA-transfected Huh7 cells treated with the transbodies produced from four different transformed E. coli clones had reduced HCV-RNA inside the cells and in the cell spent media, as well as fewer HCV foci in the cell monolayer compared to the transfected cells in culture medium alone. The transbodies-treated transfected cells also had up-expression of the genes coding for the host innate immune response, including TRIF, TRAF3, IRF3, IL-28B, and IFN-β. Computerized homology modeling and intermolecular docking predicted that the effective transbodies interacted with several critical residues of the NS3/4A protease, including those that form catalytic triads, oxyanion loop, and S1 and S6 pockets, as well as a zinc-binding site. Although insight into molecular mechanisms of the transbodies need further laboratory investigation, it can be deduced from the current data that the transbodies blocked the HCV NS3/4A protease activities, leading to the HCV replication inhibition and restoration of the virally suppressed host innate immunity. The engineered antibodies should be tested further for treatment of HCV infection either alone, in combination with current therapeutics, or in a mixture with their cognates specific to other HCV proteins.
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Affiliation(s)
- Surasak Jittavisutthikul
- Graduate Program in Immunology, Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Department of Parasitology, Faculty of Medicine Siriraj Hospital, Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Mahidol University, Bangkok, Thailand
| | - Watee Seesuay
- Department of Parasitology, Faculty of Medicine Siriraj Hospital, Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Mahidol University, Bangkok, Thailand
| | - Jeeraphong Thanongsaksrikul
- Department of Parasitology, Faculty of Medicine Siriraj Hospital, Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Mahidol University, Bangkok, Thailand
- Graduate Program in Biomedical Science, Faculty of Allied Health Sciences, Thammasat University, Pathum-thani, Thailand
| | - Kanyarat Thueng-in
- Department of Parasitology, Faculty of Medicine Siriraj Hospital, Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Mahidol University, Bangkok, Thailand
- School of Pathology, Institute of Medicine, Suranaree University of Technology, Nakhon Ratchasima Province, Thailand
| | - Potjanee Srimanote
- Graduate Program in Biomedical Science, Faculty of Allied Health Sciences, Thammasat University, Pathum-thani, Thailand
| | - Rolf G. Werner
- Industrial Technology, Faculty of Science, University of Tuebingen, Tuebingen, Germany
| | - Wanpen Chaicumpa
- Department of Parasitology, Faculty of Medicine Siriraj Hospital, Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Mahidol University, Bangkok, Thailand
- Graduate Program in Biomedical Science, Faculty of Allied Health Sciences, Thammasat University, Pathum-thani, Thailand
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2
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Martı́nez-González JÁ, González M, Masgrau L, Martı́nez R. Theoretical Study of the Free Energy Surface and Kinetics of the Hepatitis C Virus NS3/NS4A Serine Protease Reaction with the NS5A/5B Substrate. Does the Generally Accepted Tetrahedral Intermediate Really Exist? ACS Catal 2014. [DOI: 10.1021/cs5011162] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Miguel González
- Departament
de Quı́mica Fı́sica i IQTC, Universitat de Barcelona, C/Martı́ i Franquès, 1, 08028 Barcelona, Spain
| | - Laura Masgrau
- Institut
de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Rodrigo Martı́nez
- Departamento
de Quı́mica, Universidad de La Rioja, C/Madre de
Dios, 51, 26006 Logroño, Spain
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3
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Batra J, Szabó A, Caulfield TR, Soares AS, Sahin-Tóth M, Radisky ES. Long-range electrostatic complementarity governs substrate recognition by human chymotrypsin C, a key regulator of digestive enzyme activation. J Biol Chem 2013; 288:9848-9859. [PMID: 23430245 DOI: 10.1074/jbc.m113.457382] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Human chymotrypsin C (CTRC) is a pancreatic serine protease that regulates activation and degradation of trypsinogens and procarboxypeptidases by targeting specific cleavage sites within their zymogen precursors. In cleaving these regulatory sites, which are characterized by multiple flanking acidic residues, CTRC shows substrate specificity that is distinct from that of other isoforms of chymotrypsin and elastase. Here, we report the first crystal structure of active CTRC, determined at 1.9-Å resolution, revealing the structural basis for binding specificity. The structure shows human CTRC bound to the small protein protease inhibitor eglin c, which binds in a substrate-like manner filling the S6-S5' subsites of the substrate binding cleft. Significant binding affinity derives from burial of preferred hydrophobic residues at the P1, P4, and P2' positions of CTRC, although acidic P2' residues can also be accommodated by formation of an interfacial salt bridge. Acidic residues may also be specifically accommodated in the P6 position. The most unique structural feature of CTRC is a ring of intense positive electrostatic surface potential surrounding the primarily hydrophobic substrate binding site. Our results indicate that long-range electrostatic attraction toward substrates of concentrated negative charge governs substrate discrimination, which explains CTRC selectivity in regulating active digestive enzyme levels.
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Affiliation(s)
- Jyotica Batra
- Department of Cancer Biology, Mayo Clinic Cancer Center, Jacksonville, Florida 32224
| | - András Szabó
- Department of Molecular and Cell Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, Massachusetts 02118
| | - Thomas R Caulfield
- Department of Cancer Biology, Mayo Clinic Cancer Center, Jacksonville, Florida 32224; Department of Neuroscience, Mayo Clinic Cancer Center, Jacksonville, Florida 32224
| | - Alexei S Soares
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973
| | - Miklós Sahin-Tóth
- Department of Molecular and Cell Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, Massachusetts 02118.
| | - Evette S Radisky
- Department of Cancer Biology, Mayo Clinic Cancer Center, Jacksonville, Florida 32224.
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4
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Rodríguez A, Oliva C, González M. A comparative QM/MM study of the reaction mechanism of the Hepatitis C virus NS3/NS4A protease with the three main natural substrates NS5A/5B, NS4B/5A and NS4A/4B. Phys Chem Chem Phys 2010; 12:8001-15. [PMID: 20520921 DOI: 10.1039/c002116d] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The reaction mechanism of the NS3/NS4A protease with the NS4B/5A and NS4A/4B natural substrates has been investigated using the QM/MM (quantum mechanics/molecular mechanics) approach, and some calculations have been performed on the reaction with the NS5A/5B natural substrate. This study widely extends a previous contribution of our group on the reaction mechanism with the NS5A/5B substrate, the main goal here being to understand the differences found between the reaction mechanism of each natural substrate and the role played by the enzymatic residues in the catalytic cycle. This knowledge will ultimately help in developing new NS3/NS4A protease inhibitors. The two first steps of the mechanism have been considered: Acylation and breaking of the peptide bond, with emphasis on the former one (rate limiting process). Energy and free energy profiles for both steps have been calculated at the AM1/MM level and corrected by means of MP2 ab initio calculations, being evident the importance of correlation energy. Acylation is the rate limiting step in all cases and occurs through a tetracoordinated intermediate, as previously suggested for other serine proteases. Specificities in the NS4B/5A mechanism can be attributed to the presence of a Proline residue in the substrate P2 position. The analysis of structures and energies confirm the importance of the oxyanion hole in the electrostatic stabilization of the tetracoordinated intermediate. Finally, the role of other residues, e.g., Arg-155 and Asp-79, has been explained, and the viability of Arg-155 mutants and its resistance to some protease inhibitors has been understood thanks to virtual mutation studies.
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Affiliation(s)
- Alejandro Rodríguez
- Departament de Química Física i IQTC, Universitat de Barcelona, C/Martí i Franquès 1, 08028 Barcelona, Spain
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Poliakov A, Sandström A, Akerblom E, Danielson UH. Mechanistic studies of electrophilic protease inhibitors of full length hepatic C virus (HCV) NS3. J Enzyme Inhib Med Chem 2008; 22:191-9. [PMID: 17518346 DOI: 10.1080/14756360601072916] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The inhibition mechanism of electrophilic peptide-based protease inhibitors of full-length hepatitis C virus (HCV) NS3 has been investigated by determining the K(i)-values for a series of compounds differing in the electrophilicity and acidity of the C-terminal residue at pH-values above and below the pK(a) of the catalytic histidine (6.85) and at two different ionic strengths. Electrophilic compounds with a pentafluoroethyl ketone group showed stronger inhibition at pH 8 than pH 6, as expected for a mechanism requiring an unprotonated catalytic histidine. However, the difference was only significant at high ionic strength. In contrast, electrophilic compounds with an acidic C-terminal group or a cyclic P1 residue showed a lower inhibitory effect at pH 8 than at pH 6, inconsistent with a mechanism-based inhibition. Moreover, all electrophilic compounds had an unexpectedly strong inhibition at pH 6, when mechanism-based inhibition is unlikely. The results suggest that for some of the electrophilic compounds the reactive group may not be properly positioned in the active site and that binding of these inhibitors is a result of non-covalent interactions. The nature of these interactions is discussed.
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Affiliation(s)
- Anton Poliakov
- Department of Biochemistry and Organic Chemistry, Uppsala University, BMC, Box 576, Uppsala SE-751 23, Sweden
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6
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De Francesco R, Carfí A. Advances in the development of new therapeutic agents targeting the NS3-4A serine protease or the NS5B RNA-dependent RNA polymerase of the hepatitis C virus. Adv Drug Deliv Rev 2007; 59:1242-62. [PMID: 17869377 DOI: 10.1016/j.addr.2007.04.016] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Accepted: 04/13/2007] [Indexed: 01/28/2023]
Abstract
The HCV NS3 protease and NS5B polymerase play essential roles in the replication of the hepatitis C virus (HCV). Following the successful paradigm established for HIV protease and reverse transcriptase inhibitors, these enzymes have been elected as targets for the development of small molecule HCV inhibitors. By combining the power of high-throughput screening with rational, knowledge-based drug discovery, a number of competitive inhibitors of the NS3 protease as well as nucleoside and non-nucleoside inhibitors of the NS5B polymerase have been identified and some have now entered clinical trials. In this article we review recent progress in the discovery and development of small molecule inhibitors of these two essential viral enzymes as they are advancing in the clinic.
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Affiliation(s)
- Raffaele De Francesco
- Istituto di Ricerche di Biologia Molecolare, P. Angeletti, Via Pontina Km 30,600, 00040 Pomezia (Rome), Italy.
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7
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Oliva C, Rodríguez A, González M, Yang W. A quantum mechanics/molecular mechanics study of the reaction mechanism of the hepatitis C virus NS3 protease with the NS5A/5B substrate. Proteins 2007; 66:444-55. [PMID: 17094110 DOI: 10.1002/prot.21190] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Combined quantum mechanics and molecular mechanics (QM/MM) calculations were carried out to characterize the reaction mechanism of the NS3 protease with its preferred substrate (NS5A/5B). The main purpose of this study was to locate the barrier states and intermediates along the distinguished coordinate path (DCP) involved in this process. These structures, and in particular the one corresponding to the first barrier state and intermediate (B1 and I1), could be a starting point for the synthesis of inhibitors of this protease, which could be used to treat hepatitis C. The two first steps of the reaction mechanism were studied, i.e., the acylation step and the breaking of the peptide bond. The first step takes place through a tetracoordinated intermediate, as suggested from previous works on other Serine proteases. The importance of the different amino acid residues was also considered (perturbation study where the MM charges of each residue were set to zero independently). The residues of the oxyanion hole were confirmed as the most important for the electrostatic stabilization of the tetracoordinate intermediate. Moreover, the role of other residues, e.g., Arg-155 and Asp-79, was also explained.
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Affiliation(s)
- Carolina Oliva
- Departament de Química Física i Centre de Recerca en Química Teòrica, Universitat de Barcelona i Parc Científic de Barcelona, C/ Martí i Franquès 1, 08028 Barcelona, Spain.
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8
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White PW, Llinas-Brunet M, Bös M. Blunting the Swiss army knife of hepatitis C virus: inhibitors of NS3/4A protease. PROGRESS IN MEDICINAL CHEMISTRY 2006; 44:65-107. [PMID: 16697895 DOI: 10.1016/s0079-6468(05)44402-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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9
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Ferreon JC, Ferreon ACM, Li K, Lemon SM. Molecular determinants of TRIF proteolysis mediated by the hepatitis C virus NS3/4A protease. J Biol Chem 2005; 280:20483-92. [PMID: 15767257 DOI: 10.1074/jbc.m500422200] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Persistent infections with hepatitis C virus (HCV) are a major cause of liver disease and reflect its ability to disrupt virus-induced signaling pathways activating cellular antiviral defenses. HCV evasion of double-stranded RNA signaling through Toll-like receptor 3 is mediated by the viral protease NS3/4A, which directs proteolysis of its proline-rich adaptor protein, Toll-IL-1 receptor domain containing adaptor-inducing interferon-beta (TRIF). The TRIF cleavage site has remarkable homology with the viral NS4B/5A substrate, although an 8-residue polyproline track extends upstream from the P(6) position in lieu of the acidic residue present in viral substrates. Circular dichroism (CD) spectroscopy confirmed that a substantial fraction of TRIF exists as polyproline II helices, and inclusion of the polyproline track increased affinity of P side TRIF peptides for the HCV-BK protease. A polyproline II peptide representing an SH3 binding motif (PPPVPPRRR, Sos) bound NS3 with moderate affinity, resulting in inhibition of proteolytic activity. Chemical shift perturbations in NMR spectra indicated that Sos binds a 3(10) helix close to the protease active site. Thus, a polyproline II interaction with the 3(10) helix likely facilitates NS3/4A recognition of TRIF, indicating a significant difference from NS3/4A recognition of viral substrates. Because SH3 binding motifs are also present in NS5A, a viral protein that interacts with NS3, we speculate that the NS3 3(10) helix may be a site of interaction with other viral proteins.
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Affiliation(s)
- Josephine C Ferreon
- Department of Microbiology and Immunology, Center for Hepatitis Research, Institute for Human Infections and Immunity, University of Texas Medical Branch at Galveston, Galveston, Texas 77555-1019, USA
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10
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11
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Ontoria JM, Di Marco S, Conte I, Di Francesco ME, Gardelli C, Koch U, Matassa VG, Poma M, Steinkühler C, Volpari C, Harper S. The Design and Enzyme-Bound Crystal Structure of Indoline Based Peptidomimetic Inhibitors of Hepatitis C Virus NS3 Protease. J Med Chem 2004; 47:6443-6. [PMID: 15588076 DOI: 10.1021/jm049435d] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The design of a series of peptidomimetic inhibitors of the hepatitis C virus NS3 protease is described. These inhibitors feature an indoline-2-carboxamide as a novel heterocyclic replacement for the P3 amino acid residue and N-terminal capping group of tripeptide based inhibitors. The crystal structure of the ternary NS3/NS4A/inhibitor complex for the most active molecule in this series highlights its suitability as an N-terminal capping group of a dipeptide inhibitor of the NS3 protease.
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12
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Goudreau N, Brochu C, Cameron DR, Duceppe JS, Faucher AM, Ferland JM, Grand-Maître C, Poirier M, Simoneau B, Tsantrizos YS. Potent Inhibitors of the Hepatitis C Virus NS3 Protease: Design and Synthesis of Macrocyclic Substrate-Based β-Strand Mimics. J Org Chem 2004; 69:6185-201. [PMID: 15357576 DOI: 10.1021/jo049288r] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The virally encoded NS3 protease is essential to the life cycle of the hepatitis C virus (HCV), an important human pathogen causing chronic hepatitis, cirrhosis of the liver, and hepatocellular carcinoma. The design and synthesis of 15-membered ring beta-strand mimics which are capable of inhibiting the interactions between the HCV NS3 protease enzyme and its polyprotein substrate will be described. The binding interactions between a macrocyclic ligand and the enzyme were explored by NMR and molecular dynamics, and a model of the ligand/enzyme complex was developed.
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Affiliation(s)
- Nathalie Goudreau
- Department of Chemistry, Boehringer Ingelheim Ltd., Research and Development, 2100 Cunard Street, Laval, Quebec, Canada H7S 2G5
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13
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Thibeault D, Bousquet C, Gingras R, Lagacé L, Maurice R, White PW, Lamarre D. Sensitivity of NS3 serine proteases from hepatitis C virus genotypes 2 and 3 to the inhibitor BILN 2061. J Virol 2004; 78:7352-9. [PMID: 15220408 PMCID: PMC434094 DOI: 10.1128/jvi.78.14.7352-7359.2004] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Hepatitis C virus (HCV) displays a high degree of genetic variability. Six genotypes and more than 50 subtypes have been identified to date. In this report, kinetic profiles were determined for NS3 proteases of genotypes 1a, 1b, 2ac, 2b, and 3a, revealing no major differences in activity. In vitro sensitivity studies with BILN 2061 showed a decrease in affinity for proteases of genotypes 2 and 3 (K(i), 80 to 90 nM) compared to genotype 1 enzymes (K(i), 1.5 nM). To understand the reduced sensitivity of genotypes 2 and 3 to BILN 2061, active-site residues in the proximity of the inhibitor binding site were replaced in the genotype-1b enzyme with the corresponding genotype-2b or -3a residues. The replacement of five residues at positions 78, 79, 80, 122, and 132 accounted for most of the reduced sensitivity of genotype 2b, while replacement of residue 168 alone could account for the reduced sensitivity of genotype 3a. BILN 2061 remains a potent inhibitor of these non-genotype-1 NS3-NS4A proteins, with K(i) values below 100 nM. This in vitro potency, in conjunction with the good pharmacokinetic data reported for humans, suggests that there is potential for BILN 2061 as an antiviral agent for individuals infected with non-genotype-1 HCV.
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Affiliation(s)
- Diane Thibeault
- Department of Biological Sciences, Boehringer Ingelheim (Canada) Ltd, Research and Development, Laval, Québec H7S 2G5, Canada.
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Frecer V, Kabelác M, De Nardi P, Pricl S, Miertus S. Structure-based design of inhibitors of NS3 serine protease of hepatitis C virus. J Mol Graph Model 2004; 22:209-20. [PMID: 14629979 DOI: 10.1016/s1093-3263(03)00161-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have designed small focused combinatorial library of hexapeptide inhibitors of NS3 serine protease of the hepatitis C virus (HCV) by structure-based molecular design complemented by combinatorial optimisation of the individual residues. Rational residue substitutions were guided by the structure and properties of the binding pockets of the enzyme's active site. The inhibitors were derived from peptides known to inhibit the NS3 serine protease by using unusual amino acids and alpha-ketocysteine or difluoroaminobutyric acid, which are known to bind to the S1 pocket of the catalytic site. Inhibition constants (Ki) of the designed library of inhibitors were predicted from a QSAR model that correlated experimental Ki of known peptidic inhibitors of NS3 with the enthalpies of enzyme-inhibitor interaction computed via molecular mechanics and the solvent effect contribution to the binding affinity derived from the continuum model of solvation. The library of the optimised inhibitors contains promising drug candidates-water-soluble anionic hexapeptides with predicted Ki* in the picomolar range.
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Affiliation(s)
- Vladimír Frecer
- International Centre for Science and High Technology, UNIDO, AREA Science Park, Padriciano 99, I-34012, Trieste, Italy
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15
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Tsantrizos YS. The design of a potent inhibitor of the hepatitis C virus NS3 protease:BILN 2061?From the NMR tube to the clinic. Biopolymers 2004; 76:309-23. [PMID: 15386268 DOI: 10.1002/bip.20127] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The virally encoded serine protease NS3/NS4A is essential to the life cycle of the hepatitis C virus (HCV), an important human pathogen causing chronic hepatitis, cirrhosis of the liver, and hepatocellular carcinoma. Until very recently, the design of inhibitors for the HCV NS3 protease was limited to large peptidomimetic compounds with poor pharmacokinetic properties, making drug discovery an extremely challenging endeavor. In our quest for the discovery of a small-molecule lead that could block replication of the hepatitis C virus by binding to the HCV NS3 protease, the critical protein-polypeptide interactions between the virally encoded NS3 serine protease and its polyprotein substrate were investigated. Lead optimization of a substrate-based hexapeptide, guided by structural data, led to the understanding of the molecular dynamics and electronic effects that modulate the affinity of peptidomimetic ligands for the active site of this enzyme. Macrocyclic beta-strand scaffolds were designed that allowed the discovery of potent, highly selective, and orally bioavailable compounds. These molecules were the first HCV NS3 protease inhibitors reported that inhibit replication of HCV subgenomic RNA in a cell-based replicon assay at low nanomolar concentrations. Optimization of their biopharmaceutical properties led to the discovery of the clinical candidate BILN 2061. Oral administration of BILN 2061 to patients infected with the hepatitis C genotype 1 virus resulted in an impressive reduction of viral RNA levels, establishing proof-of-concept for HCV NS3 protease inhibitors as therapeutic agents in humans.
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Affiliation(s)
- Youla S Tsantrizos
- Boehringer Ingelheim (Canada) Ltd., Research and Development, 2100 Cunard Street, Laval (Québec) H7S 2G5, Canada.
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Trozzi C, Bartholomew L, Ceccacci A, Biasiol G, Pacini L, Altamura S, Narjes F, Muraglia E, Paonessa G, Koch U, De Francesco R, Steinkuhler C, Migliaccio G. In vitro selection and characterization of hepatitis C virus serine protease variants resistant to an active-site peptide inhibitor. J Virol 2003; 77:3669-79. [PMID: 12610142 PMCID: PMC149541 DOI: 10.1128/jvi.77.6.3669-3679.2003] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2002] [Accepted: 12/13/2002] [Indexed: 01/08/2023] Open
Abstract
The hepatitis C virus (HCV) serine protease is necessary for viral replication and represents a valid target for developing new therapies for HCV infection. Potent and selective inhibitors of this enzyme have been identified and shown to inhibit HCV replication in tissue culture. The optimization of these inhibitors for clinical development would greatly benefit from in vitro systems for the identification and the study of resistant variants. We report the use HCV subgenomic replicons to isolate and characterize mutants resistant to a protease inhibitor. Taking advantage of the replicons' ability to transduce resistance to neomycin, we selected replicons with decreased sensitivity to the inhibitor by culturing the host cells in the presence of the inhibitor and neomycin. The selected replicons replicated to the same extent as those in parental cells. Sequence analysis followed by transfection of replicons containing isolated mutations revealed that resistance was mediated by amino acid substitutions in the protease. These results were confirmed by in vitro experiments with mutant enzymes and by modeling the inhibitor in the three-dimensional structure of the protease.
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De Francesco R, Tomei L, Altamura S, Summa V, Migliaccio G. Approaching a new era for hepatitis C virus therapy: inhibitors of the NS3-4A serine protease and the NS5B RNA-dependent RNA polymerase. Antiviral Res 2003; 58:1-16. [PMID: 12719002 DOI: 10.1016/s0166-3542(03)00028-7] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The treatment of chronic disease caused by the hepatitis C virus (HCV) is an unmet clinical need, since current therapy is only partially effective and limited by undesirable side effects. The viral serine protease and the RNA-dependent RNA polymerase are the best-studied targets for the development of novel therapeutic agents. These enzymes have been extensively characterized at the biochemical and structural level and thus used to set up screening assays for the identification of selective inhibitors. These efforts lead to the discovery of several classes of compounds with potential antiviral activity. The hepatitis C virus does not replicate in the laboratory. The formidable challenge posed by the difficulty of developing cell-based assays and preclinical animal systems has been partially overcome with several alternative approaches. The development of new assays permitted the optimization of enzyme inhibitors leading eventually to molecules with the desired drug-like properties, the most advanced of which are being considered for clinical trials.
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Affiliation(s)
- Raffaele De Francesco
- Instituto di Ricerche di Biologia Molecolare, P. Angeletti, 00040 Pomezia-Rome, Italy.
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Narjes F, Koch U, Steinkühler C. Recent developments in the discovery of hepatitis C virus serine protease inhibitors--towards a new class of antiviral agents? Expert Opin Investig Drugs 2003; 12:153-63. [PMID: 12556211 DOI: 10.1517/13543784.12.2.153] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hepatitis C virus (HCV) infection is an epidemic disease and a significant worldwide health problem. Despite impressive improvements in the efficacy of the standard, interferon-based therapies, at present, the virus can not be eradicated in the majority of infected individuals. The last decade has witnessed a burst in our understanding of the molecular biology of HCV infection and lead to the identification of essential features of the viral genome that are being targeted for the development of specific antiviral agents. The non-structural protein 3 of the HCV genome harbours a serine protease domain that is essential for viral replication. This enzyme has been studied in great detail and the wealth of structural and functional data are presently nurturing drug development efforts. The peculiar active site structure of the enzyme imposes considerable obstacles to the development of small molecule inhibitors. However, the combination of creativity with the powerful tools of modern drug discovery has led to impressive progress in this field over the past few years and, as a result, the first compounds are now entering clinical trials.
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Affiliation(s)
- Frank Narjes
- Instituto di Ricerche di Biologia Molecolare-Merck Research Laboratories Rome,Via Pontina Km 30,600,00040 Pomezia, Italy
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19
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Colarusso S, Koch U, Gerlach B, Steinkühler C, De Francesco R, Altamura S, Matassa VG, Narjes F. Phenethyl amides as novel noncovalent inhibitors of hepatitis C virus NS3/4A protease: discovery, initial SAR, and molecular modeling. J Med Chem 2003; 46:345-8. [PMID: 12540231 DOI: 10.1021/jm025594q] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
The discovery of novel, reversible and competitive tripeptide inhibitors of the Hepatitis C virus NS3/4A serine protease is described. These inhibitors are characterized by the presence of a C-terminal phenethyl amide group, which extends into the prime side of the enzyme. Initial SAR together with molecular modeling and data from site-directed mutagenesis suggest an interaction of the phenethyl amide group with Lys-136.
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Affiliation(s)
- Stefania Colarusso
- Department of Chemistry, IRBM--MRL Rome, Via Pontina Km 30.600, 00040 Pomezia, Italy
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20
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Affiliation(s)
- Liang Tong
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
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21
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Johansson A, Poliakov A, Akerblom E, Lindeberg G, Winiwarter S, Samuelsson B, Danielson UH, Hallberg A. Tetrapeptides as potent protease inhibitors of Hepatitis C Virus full-length NS3 (protease-helicase/NTPase). Bioorg Med Chem 2002; 10:3915-22. [PMID: 12413843 DOI: 10.1016/s0968-0896(02)00310-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A library of tetrapeptides was evaluated for Hepatitis C Virus NS3 protease inhibitor activity in an in vitro assay system comprising the native bifunctional full-length NS3 (protease-helicase/NTPase) protein. Tetrapeptides with K(i) values in the high nanomolar range were identified, for example Suc-Chg-Glu-2-Nal-Cys (K(i)=0.27+/-0.03 microM) and Suc-Dif-Glu-Glu-Cys (K(i)=0.40+/-0.10 microM). Furthermore, it was shown that the inhibitory potencies are not affected significantly by assay ionic strength. As suggested by molecular modelling, potential binding interactions of the tetrapeptide inhibitors with the helicase domain might explain the data and structure-activity relationships thus obtained. Hence, we postulate that the full-length NS3 assay is a relevant system for inhibitor identification, offering new opportunities for inhibitor design.
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Affiliation(s)
- Anja Johansson
- Department of Medicinal Chemistry, Uppsala University, BMC, Box 574, SE-751 23 Uppsala, Sweden
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22
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Abstract
Inhibitor design against viral targets must take into account the peculiar characteristics of viral biology-in particular, the plasticity of their replicative machinery. This includes maturational cleavage of the polyprotein, which is mediated by virally encoded proteases. Designing against a movable target is particularly challenging, but at the same time it offers new opportunities. Here we describe our experience with the NS3/4A (NS: nonstructural) serine protease of human hepatitis C virus (HCV). By extensive use of combinatorial peptide libraries, various inhibitor types were generated, including product inhibitors, serine traps, P-P' inhibitors, and prime side inhibitors. The latter represent a first case for a serine protease. A key finding, derived from structural studies utilizing these inhibitors, was that NS3 is an induced-fit protease, requiring both the NS4A cofactor protein and the substrate to fully activate its catalytic machinery. In the absence of cofactor and/or substrate, NS3 exists in solution as a large conformational ensemble, which can be matched by a correspondingly large set of peptide inhibitors, each one stabilizing a given conformer. In the perspective of inhibiting viral proteases in general, we suggest that combinatorial ligand ensembles may be a powerful tool, to contrast the adaptive potential of the viral quasispecies.
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Affiliation(s)
- Elisabetta Bianchi
- Biopolymers Laboratory, Department of Molecular & Cell Biology, IRBM P. Angeletti, Via Pontina Km 30.600, 00040 Pomezia, Rome, Italy
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23
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Nizi E, Koch U, Ponzi S, Matassa VG, Gardelli C. Capped dipeptide alpha-ketoacid inhibitors of the HCV NS3 protease. Bioorg Med Chem Lett 2002; 12:3325-8. [PMID: 12392743 DOI: 10.1016/s0960-894x(02)00691-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The N-terminal aminoacid of alpha-ketotripeptide inhibitors of the hepatitis C virus NS3 protease can be replaced with an alpha-hydroxy acid, leading to capped dipeptide inhibitors such as 20 with an IC(50) value of 3.0 microM. The importance of the lipophilic side chain interactions at S3 of the protease and the requirement of the capping residue with R configuration have been explained by molecular modeling studies.
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Affiliation(s)
- Emanuela Nizi
- Department of Chemistry, IRBM, MRL Rome, Via Pontina Km 30,600, Pomezia, 00040 Rome, Italy
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24
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Poliakov A, Hubatsch I, Shuman CF, Stenberg G, Danielson UH. Expression and purification of recombinant full-length NS3 protease-helicase from a new variant of Hepatitis C virus. Protein Expr Purif 2002; 25:363-71. [PMID: 12182815 DOI: 10.1016/s1046-5928(02)00042-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Viral mRNA extracted from the serum of a patient infected with HCV strain 1a was used for cloning, expression, and purification of full-length Hepatitis C NS3 protein. Sequencing of the protease gene identified the virus to be a new variant closely related to strain H77, differing in 15 out of 631 amino acids in the NS3 protein, none of which were predicted to be directly involved in catalysis, binding of substrate, or cofactor. A pBAD expression system was used to express the enzyme with an N-terminal tag in Escherichia coli. Purification from the soluble cellular fraction was achieved by Ni(2+)-IMAC and PolyU Sepharose affinity chromatography. The dependence of the proteolytic activity of the full-length NS3 protein on ionic strength, glycerol concentration, and a peptide corresponding to the activating region of NS4A was analyzed and used to design an activity assay that is suitable for inhibition studies. The kinetic constants (k(cat) and K(M)) for catalysis and the inhibitory potencies (IC(50) and K(i)) of five product-based hexapeptide inhibitors were comparable to those reported for the truncated NS3 protein. Detailed kinetic and inhibition studies using this variant of full-length NS3 can increase the understanding of the enzymatic characteristics of NS3, reveal the importance of the substituted amino acids and the significance of the genetic variability for design of effective inhibitors of the virus, and is thus of relevance for drug discovery.
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Affiliation(s)
- Anton Poliakov
- Department of Biochemistry, Uppsala University, BMC, Box 576, SE-751 23 Uppsala, Sweden
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25
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Steinkühler C, Biasiol G, Cerretani M, Di Renzo L, Brunetti M, Ingallinella P, De Francesco R, Altamura S. A scintillation proximity active site binding assay for the hepatitis C virus serine protease. Anal Biochem 2002; 307:99-104. [PMID: 12137785 DOI: 10.1016/s0003-2697(02)00013-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A binding assay suitable for the identification of active site-directed inhibitors of the hepatitis C virus serine protease NS3 was developed. A C-terminal extension of 13 residues that is specifically recognized by the Escherichia coli biotin holoenzyme synthetase (Bir A) was fused to a truncated NS3 protease domain, allowing the efficient production of in vivo biotinylated protease. This enzyme was purified and shown to have the same properties as its wild-type counterpart concerning substrate binding and turnover, interaction with a cofactor peptide, and inhibition by three different classes of inhibitors. Immobilization of the biotinylated protease, using streptavidin-coated scintillation proximity beads, allowed detection, by scintillation counting, of its interaction with a tritiated active site ligand spanning the whole substrate binding site of the protease from P6 to P4('). Immobilization did not measurably affect accessibility to either the active site or the cofactor binding site of the protease as judged by the unchanged affinities for a cofactor peptide and for two active site binders. Using the displacement of the radioligand as readout, we were able to set up a rapid, robust, and fully automated assay, suitable for the selective identification of novel active site ligands of the NS3 protease.
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Affiliation(s)
- Christian Steinkühler
- Department of Biochemistry, Istituto di Ricerche di Biologia Molecolare P.Angeletti (IRBM), Merck Research Laboratories, Rome, Italy
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26
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Colarusso S, Gerlach B, Koch U, Muraglia E, Conte I, Stansfield I, Matassa VG, Narjes F. Evolution, synthesis and SAR of tripeptide alpha-ketoacid inhibitors of the hepatitis C virus NS3/NS4A serine protease. Bioorg Med Chem Lett 2002; 12:705-8. [PMID: 11844706 DOI: 10.1016/s0960-894x(01)00843-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
N-terminal truncation of the hexapeptide ketoacid 1 gave rise to potent tripeptide inhibitors of the hepatitis C virus NS3 protease/NS4A cofactor complex. Optimization of these tripeptides led to ketoacid 30 with an IC50 of 0.38 microM. The SAR of these tripeptides is discussed in the light of the recently published crystal structures of a ternary tripetide/NS3/NS4A complexes.
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Affiliation(s)
- Stefania Colarusso
- Department of Chemistry, IRBM, MRL Rome, Via Pontina Km 30.600, Pomezia, 00040, Rome, Italy
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27
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Narjes F, Koehler KF, Koch U, Gerlach B, Colarusso S, Steinkühler C, Brunetti M, Altamura S, De Francesco R, Matassa VG. A designed P1 cysteine mimetic for covalent and non-covalent inhibitors of HCV NS3 protease. Bioorg Med Chem Lett 2002; 12:701-4. [PMID: 11844705 DOI: 10.1016/s0960-894x(01)00842-3] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The difluoromethyl group was designed by computational chemistry methods as a mimetic of the canonical P1 cysteine thiol for inhibitors of the hepatitis C virus NS3 protease. This modification led to the development of competitive, non-covalent inhibitor 4 (K(i) 30 nM) and reversible covalent inhibitors (6, K(i) 0.5 nM; and 8 K*(i) 10 pM).
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Affiliation(s)
- Frank Narjes
- Department of Chemistry, IRBM, MRL Rome, Via Pontina Km 30.600, Pomezia, 00040, Rome, Italy.
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28
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Yeung KS, Meanwell NA, Qiu Z, Hernandez D, Zhang S, McPhee F, Weinheimer S, Clark JM, Janc JW. Structure-activity relationship studies of a bisbenzimidazole-based, Zn(2+)-dependent inhibitor of HCV NS3 serine protease. Bioorg Med Chem Lett 2001; 11:2355-9. [PMID: 11527730 DOI: 10.1016/s0960-894x(01)00457-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A survey of isosteric replacements of the phosphonoalanine side chain coupled with a process of conformational constraint of a bisbenzimidazole-based, Zn(2+)-dependent inhibitor of hepatitis C virus (HCV) NS3 serine protease resulted in the identification of novel series of active compounds with extended side chains. However, Zn(2+)-dependent HCV NS3 inhibition was relatively insensitive to the structural variations examined but dependent on the presence of negatively charged functionality. This result was interpreted in the context of an initial electrostatic interaction between protease and inhibitor that is subsequently consolidated by Zn(2+), with binding facilitated by the featureless active site and proximal regions of the HCV NS3 protein.
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Affiliation(s)
- K S Yeung
- Bristol-Myers Squibb Pharmaceutical Research Institute, 5 Research Parkway, POBox 5100, Wallingford, CT 06492, USA.
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