1oh0

From Proteopedia

Revision as of 13:49, 30 October 2007

CRYSTAL STRUCTURE OF KETOSTEROID ISOMERASE COMPLEXED WITH EQUILENIN

Overview

Bacterial Delta5-3-ketosteroid isomerase (KSI) catalyzes a stereospecific, isomerization of steroid substrates at an extremely fast rate, overcoming, a large disparity of pKa values between a catalytic residue and its, target. The crystal structures of KSI from Pseudomonas putida and of the, enzyme in complex with equilenin, an analogue of the reaction, intermediate, have been determined at 1.9 and 2.5 A resolution, respectively. The structures reveal that the side chains of Tyr14 and, Asp99 (a newly identified catalytic residue) form hydrogen bonds directly, with the oxyanion of the bound inhibitor in a completely apolar milieu of, the active site. No water molecule is found at the active site, and the, access of bulk solvent is blocked by a layer of apolar residues. Asp99 is, surrounded ... [(full description)]

About this Structure

1OH0 is a [Single protein] structure of sequence from [Pseudomonas putida] with EQU and BME as [ligands]. This structure superseeds the now removed PDB entry 4TSU. Active as [Steroid Delta-isomerase], with EC number [5.3.3.1]. Structure known Active Site: AC1. Full crystallographic information is available from [OCA].

Reference

High-resolution crystal structures of delta5-3-ketosteroid isomerase with and without a reaction intermediate analogue., Kim SW, Cha SS, Cho HS, Kim JS, Ha NC, Cho MJ, Joo S, Kim KK, Choi KY, Oh BH, Biochemistry. 1997 Nov 18;36(46):14030-6. PMID:9369474

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