2oqx

From Proteopedia

Revision as of 10:32, 23 January 2008

Crystal Structure of the apo form of E. coli tryptophanase at 1.9 A resolution

Overview

The crystal structure of apo tryptophanase from Escherichia coli (space, group F222, unit-cell parameters a = 118.4, b = 120.1, c = 171.2 A) was, determined at 1.9 A resolution using the molecular-replacement method and, refined to an R factor of 20.3% (R(free) = 23.2%). The structure revealed, a significant shift in the relative orientation of the domains compared, with both the holo form of Proteus vulgaris tryptophanase and with another, crystal structure of apo E. coli tryptophanase, reflecting the internal, flexibility of the molecule. Domain shifts were previously observed in, tryptophanase and in the closely related enzyme tyrosine phenol-lyase, with the holo form found in an open conformation and the apo form in, either an open or a closed conformation. Here, a wide-open conformation of, the apo form of tryptophanase is reported. A conformational change is also, observed in loop 297-303. The structure contains a hydrated Mg(2+) at the, cation-binding site and a Cl(-) ion at the subunit interface. The enzyme, activity depends on the nature of the bound cation, with smaller ions, serving as inhibitors. It is hypothesized that this effect arises from, variations of the coordination geometry of the bound cation.

About this Structure

2OQX is a Single protein structure of sequence from Escherichia coli with , and as ligands. Active as Tryptophanase, with EC number 4.1.99.1 Full crystallographic information is available from OCA.

Reference

The structure of apo tryptophanase from Escherichia coli reveals a wide-open conformation., Tsesin N, Kogan A, Gdalevsky GY, Himanen JP, Cohen-Luria R, Parola AH, Goldgur Y, Almog O, Acta Crystallogr D Biol Crystallogr. 2007 Sep;63(Pt 9):969-74. Epub 2007, Aug 17. PMID:17704565

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