1m21
From Proteopedia
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Crystal structure analysis of the peptide amidase PAM in complex with the competitive inhibitor chymostatin
Overview
The peptide amidase from Stenotrophomonas maltophilia catalyses, predominantly the hydrolysis of the C-terminal amide bond in peptide, amides. Peptide bonds or amide functions in amino acid side-chains are not, hydrolysed. This specificity makes peptide amidase (Pam) interesting for, different biotechnological applications. Pam belongs to the amidase, signature (AS) family. It is the first protein within this family whose, tertiary structure has been solved. The structure of the native Pam has, been determined with a resolution of 1.4A and in complex with the, competitive inhibitor chymostatin at a resolution of 1.8A. Chymostatin, which forms acyl adducts with many serine proteases, binds non-covalently, to this enzyme.Pam folds as a very compact single-domain protein. The AS, sequence represents a core domain that is covered by alpha-helices. This, AS domain contains the catalytic residues. It is topologically homologous, to the phosphoinositol phosphatase domain.The structural data do not, support the recently proposed Ser-Lys catalytic dyad mechanism for AS, enzymes. Our results are in agreement with the role of Ser226 as the, primary nucleophile but differ concerning the roles of Ser202 and Lys123:, Ser202, with direct contact both to the substrate molecule and to Ser226, presumably serves as an acid/bases catalyst. Lys123, with direct contact, to Ser202 but no contact to Ser226 or the substrate molecule, most likely, acts as an acid catalyst.
About this Structure
1M21 is a Single protein structure of sequence from Stenotrophomonas maltophilia with CHY as ligand. Full crystallographic information is available from OCA.
Reference
An alternative mechanism for amidase signature enzymes., Labahn J, Neumann S, Buldt G, Kula MR, Granzin J, J Mol Biol. 2002 Oct 4;322(5):1053-64. PMID:12367528
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