1lcp
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BOVINE LENS LEUCINE AMINOPEPTIDASE COMPLEXED WITH L-LEUCINE PHOSPHONIC ACID
OverviewOverview
The three-dimensional structure of bovine lens leucine aminopeptidase, (blLAP) complexed with L-Leucinephosphonic acid (LeuP) has been determined, by molecular replacement using the structure of native blLAP as a starting, model. Cocrystallization of the enzyme with the inhibitor yielded a new, crystal form of space group P321 which has cell dimensions a = 130.4 A and, c = 125.4 A. Refinement of the model against data from 7.0 to 1.65 A, resolution resulted in a final structure with a crystallographic residual, of 0.160 (R(free) = 0.191). The N-terminal amino group of LeuP is, coordinated to Zn-489, one phosphoryl oxygen atom bridges both metal ions, and another phosphoryl oxygen atom is coordinated to Zn-488. The side, chain of Arg-336 interacts with the inhibitor via three water molecules., LeuP resembles the presumed tetrahedral gem-diolate transition state after, direct attack of a water or hydroxide ion nucleophile on the scissile, peptide bond. On the basis of the LeuP binding mode and the previous, structural and biochemical data, three plausible reaction pathways are, evaluated. The two-metal ion mechanisms discussed herein share as common, features a metal-bound hydroxide ion nucleophile and polarization of the, carbonyl group by the zinc ions. Possible catalytic roles of Arg-336 and, Lys-262 in the direct or indirect (through H2O) protonation of the leaving, group, in the stabilization of a zinc-bound OH- nucleophile and in the, stabilization of the negatively charged intermediate, are discussed. A, site 3 metal ion approximately 12 A away from the active site 2 zinc ion, probably serves a structural role.
About this StructureAbout this Structure
1LCP is a Single protein structure of sequence from Bos taurus with ZN, PLU and MRD as ligands. Active as Leucyl aminopeptidase, with EC number 3.4.11.1 Full crystallographic information is available from OCA.
ReferenceReference
Transition state analogue L-leucinephosphonic acid bound to bovine lens leucine aminopeptidase: X-ray structure at 1.65 A resolution in a new crystal form., Strater N, Lipscomb WN, Biochemistry. 1995 Jul 18;34(28):9200-10. PMID:7619821
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