1lam
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LEUCINE AMINOPEPTIDASE (UNLIGATED)
OverviewOverview
The three-dimensional structures of bovine lens leucine aminopeptidase, (blLAP) complexed with L-leucinal and of the unliganded enzyme have been, determined at crystallographic resolutions of 1.9 and 1.6 A, respectively., Leucinal binds as a hydrated gem-diol to the active site of b1LAP), resembling the presumed gem-diolated intermediate in the catalytic, pathway. One hydroxyl group bridges the two active site metal ions, and, the other OH group is coordinated to Zn1. The high-resolution structure of, the unliganded enzyme reveals one metal-bound water ligand, which is, bridging both zinc ions. Together, these structures support a mechanism in, which the bridging water ligand is the attacking hydroxide ion, nucleophile. The gem-diolate intermediate is probably stabilized by four, coordinating bonds to the dizinc center and by interaction with Lys-262, and Arg-336. In the mechanism, Lys-262 polarizes the peptide carbonyl, group, which is also coordinated to Zn1. The Arg-336 side chain interacts, with the substrate and the gem-diolate intermediate via water molecules., Near Arg-336 in the b1LAP-leucinal structure, an unusually short hydrogen, bond is found between two active site water molecules.
About this StructureAbout this Structure
1LAM is a Single protein structure of sequence from Bos taurus with ZN, CO3 and MRD as ligands. Active as Leucyl aminopeptidase, with EC number 3.4.11.1 Full crystallographic information is available from OCA.
ReferenceReference
Two-metal ion mechanism of bovine lens leucine aminopeptidase: active site solvent structure and binding mode of L-leucinal, a gem-diolate transition state analogue, by X-ray crystallography., Strater N, Lipscomb WN, Biochemistry. 1995 Nov 14;34(45):14792-800. PMID:7578088
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