1LAM

LEUCINE AMINOPEPTIDASE (UNLIGATED)

Summary for 1LAM

• Entry DOI: 10.2210/pdb1lam/pdb
• Descriptor: LEUCINE AMINOPEPTIDASE, ZINC ION, CARBONATE ION, ... (5 entities in total)
• Functional Keywords: aminopeptidase, exopeptidase, metallopeptidase, hydrolase (alpha-aminoacylpeptide)
• Biological source: Bos taurus (cattle)
• Cellular location: Cytoplasm: P00727
• Total number of polymer chains: 1
• Total formula weight: 53279.61

Authors

Straeter, N.,Lipscomb, W.N. (deposition date: 1995-08-11, release date: 1995-10-15, Last modification date: 2024-02-14)

Primary citation

Strater, N.,Lipscomb, W.N.
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.
Biochemistry, 34:14792-14800, 1995

PubMed Abstract: 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.

PubMed: 7578088
DOI: 10.1021/bi00045a021

Experimental method

X-RAY DIFFRACTION (1.6 Å)