title: A continuous assay for foot-and-mouth disease virus 3C protease activity.
abstract: Foot-and-mouth disease virus is a highly contagious pathogen that spreads rapidly among livestock and is capable of causing widespread agricultural and economic devastation. The virus genome is translated to produce a single polypeptide chain that subsequently is cleaved by viral proteases into mature protein products, with one protease, 3C(pro), carrying out the majority of the cleavages. The highly conserved nature of this protease across different viral strains and its crucial role in viral maturation and replication make it a very desirable target for inhibitor design. However, the lack of a convenient and high-throughput assay has been a hindrance in the characterization of potential inhibitors. In this article, we report the development of a continuous assay with potential for high throughput using fluorescence resonance energy transfer-based peptide substrates. Several peptide substrates containing the 3C-specific cleavage site were synthesized, varying both the positions and separation of the fluorescent donor and quencher groups. The best substrate, with a specificity constant k(cat)/K(M) of 57.6+/-2.0M(-1) s(-1), was used in inhibition assays to further characterize the protease's activity against a range of commercially available inhibitors. The inhibition profile of the enzyme showed characteristics of both cysteine and serine proteases, with the chymotrypsin inhibitor TPCK giving stoichiometric inhibition of the enzyme and allowing active site titration of the 3C(pro).
authors.affiliation: Department of Chemistry, Imperial College, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Agnès M
authors.initials: AM
authors.lastname: Jaulent
authors.forename: Aodhnait S
authors.initials: AS
authors.lastname: Fahy
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Knox
authors.forename: James R
authors.initials: JR
authors.lastname: Birtley
authors.forename: Núria
authors.initials: N
authors.lastname: Roqué-Rosell
authors.forename: Stephen
authors.initials: S
authors.lastname: Curry
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Leatherbarrow
mesh_terms: D000086042:3C Viral Proteases; D003546:Cysteine Endopeptidases / Q000032:analysis*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D006868:Hydrolysis; D007700:Kinetics; D009282:Naphthalenesulfonates / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D013379:Substrate Specificity; D014764:Viral Proteins / Q000032:analysis* / Q000037:antagonists & inhibitors; D004124:p-Dimethylaminoazobenzene / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism
chemical_list: D015853:Cysteine Proteinase Inhibitors; D009282:Naphthalenesulfonates; D010455:Peptides; D015842:Serine Proteinase Inhibitors; D014764:Viral Proteins; C063126:5-((2-aminoethyl)amino)naphthalene-1-sulfonic acid; C063127:4-(4-dimethylaminophenylazo)benzoic acid; D004124:p-Dimethylaminoazobenzene; D003546:Cysteine Endopeptidases; D000086042:3C Viral Proteases