2bww
|
HIS350ALA ESCHERICHIA COLI AMINOPEPTIDASE P
OverviewOverview
Aminopeptidase P (APPro) is a manganese-dependent enzyme that cleaves the, N-terminal amino acid from polypeptides where the second residue is, proline. APPro shares a similar fold, substrate specificity, and catalytic, mechanism with methionine aminopeptidase and prolidase. To investigate the, roles of conserved residues at the active site, seven mutant forms of, APPro were characterized kinetically and structurally. Mutation of, individual metal ligands selectively abolished binding of either or both, Mn(II) atoms at the active site, and none of these metal-ligand mutants, had detectable catalytic activity. Mutation of the conserved active site, residues His243 and His361 revealed that both are required for catalysis., We propose that His243 stabilizes substrate binding through an interaction, with the carbonyl oxygen of the requisite proline residue of a substrate, and that His361 stabilizes substrate binding and the gem-diol catalytic, intermediate. Sequence, structural, and kinetic analyses reveal that, His350, conserved in APPro and prolidase but not in methionine, aminopeptidase, forms part of a hydrophobic binding pocket that gives, APPro its proline specificity. Further, peptides in which the required, proline residue is replaced by N-methylalanine or alanine are cleaved by, APPro, but they are extremely poor substrates due to a loss of, interactions between the prolidyl ring of the substrate and the, hydrophobic proline-binding pocket.
About this StructureAbout this Structure
2BWW is a Single protein structure of sequence from Escherichia coli with MN, MG, FLC and MRD as ligands. Active as Xaa-Pro aminopeptidase, with EC number 3.4.11.9 Structure known Active Site: AC1. Full crystallographic information is available from OCA.
ReferenceReference
Kinetic and crystallographic analysis of mutant Escherichia coli aminopeptidase P: insights into substrate recognition and the mechanism of catalysis., Graham SC, Lilley PE, Lee M, Schaeffer PM, Kralicek AV, Dixon NE, Guss JM, Biochemistry. 2006 Jan 24;45(3):964-75. PMID:16411772
Page seeded by OCA on Mon Nov 5 17:51:21 2007