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spinqualitylabelsall models 1ft7, resolution 2.2Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

AAP COMPLEXED WITH L-LEUCINEPHOSPHONIC ACID

Overview

The nature of the interaction of the transition-state analogue inhibitor, L-leucinephosphonic acid (LPA) with the leucine aminopeptidase from, Aeromonas proteolytica (AAP) was investigated. LPA was shown to be a, competitive inhibitor at pH 8.0 with a K(i) of 6.6 microM. Electronic, absorption spectra, recorded at pH 7.5 of [CoCo(AAP)], [CoZn(AAP)], and, [ZnCo(AAP)] upon addition of LPA suggest that LPA interacts with both, metal ions in the dinuclear active site. EPR studies on the, Co(II)-substituted forms of AAP revealed that the environments of the, Co(II) ions in both [CoZn(AAP)] and [ZnCo(AAP)] become highly asymmetric, and constrained upon the addition of LPA and clearly indicate that LPA, interacts with both metal ions. The X-ray crystal structure of AAP, complexed with LPA was determined at 2.1 A resolution. The X-ray, crystallographic data indicate that LPA interacts with both metal centers, in the dinuclear active site of AAP and a single oxygen atom bridge is, absent. Thus, LPA binds to the dinuclear active site of AAP as an, eta-1,2-mu-phosphonate with one ligand to the second metal ion provided by, the N-terminal amine. A structural comparison of the binding of, phosphonate-containing transition-state analogues to the mono- and, bimetallic peptidases provides insight into the requirement for the second, metal ion in bridged bimetallic peptidases. On the basis of the results, obtained from the spectroscopic and X-ray crystallographic data presented, herein along with previously reported mechanistic data for AAP, a new, catalytic mechanism for the hydrolysis reaction catalyzed by AAP is, proposed.

About this Structure

1FT7 is a Single protein structure of sequence from Vibrio proteolyticus with ZN, K and PLU as ligands. Active as Bacterial leucyl aminopeptidase, with EC number 3.4.11.10 Full crystallographic information is available from OCA.

Reference

Inhibition of the aminopeptidase from Aeromonas proteolytica by L-leucinephosphonic acid. Spectroscopic and crystallographic characterization of the transition state of peptide hydrolysis., Stamper C, Bennett B, Edwards T, Holz RC, Ringe D, Petsko G, Biochemistry. 2001 Jun 19;40(24):7035-46. PMID:11401547

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