2z3c
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A Mechanistic view of Enzyme Inhibition and Peptide Hydrolysis in the Active Site of the SARS-CoV 3C-Like peptidase
OverviewOverview
The 3C-like main peptidase 3CL(pro) is a viral polyprotein processing, enzyme essential for the viability of the Severe Acute Respiratory, Syndrome coronavirus (SARS-CoV). While it is generalized that 3CL(pro) and, the structurally related 3C(pro) viral peptidases cleave their substrates, via a mechanism similar to that underlying the peptide hydrolysis by, chymotrypsin-like serine proteinases (CLSPs), some of the hypothesized key, intermediates have not been structurally characterized. Here, we present, three crystal structures of SARS 3CL(pro) in complex with each of two, members of a new class of peptide-based phthalhydrazide inhibitors. Both, inhibitors form an unusual thiiranium ring with the nucleophilic sulfur, atom of Cys145, trapping the enzyme's catalytic residues in configurations, similar to the intermediate states proposed to exist during the hydrolysis, of native substrates. Most significantly, our crystallographic data are, consistent with a scenario in which a water molecule, possibly via, indirect coordination from the carbonyl oxygen of Thr26, has initiated, nucleophilic attack on the enzyme-bound inhibitor. Our data suggest that, this structure resembles that of the proposed tetrahedral intermediate, during the deacylation step of normal peptidyl cleavage.
About this StructureAbout this Structure
2Z3C is a Single protein structure of sequence from Sars coronavirus with , , and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
A mechanistic view of enzyme inhibition and peptide hydrolysis in the active site of the SARS-CoV 3C-like peptidase., Yin J, Niu C, Cherney MM, Zhang J, Huitema C, Eltis LD, Vederas JC, James MN, J Mol Biol. 2007 Aug 24;371(4):1060-74. Epub 2007 Jun 8. PMID:17599357
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