1ch0

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Revision as of 10:19, 20 November 2007

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spinqualitylabelsall models 1ch0, resolution 2.3Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

RNASE T1 VARIANT WITH ALTERED GUANINE BINDING SEGMENT

Overview

The ribonuclease T1 variant 9/5 with a guanine recognition segment, altered from the wild-type amino acid sequence 41-KYNNYE-46 to, 41-EFRNWQ-46, has been cocrystallised with the specific inhibitor 2'-GMP., The crystal structure has been refined to a crystallographic R factor of, 0.198 at 2.3 A resolution. Despite a size reduction of the binding pocket, pushing the inhibitor outside by 1 A, 2'-GMP is fixed to the primary, recognition site due to increased aromatic stacking interactions. The, phosphate group of 2'-GMP is located about 4.2 A apart from its position, in wild-type ribonuclease T1-2'-GMP complexes, allowing a Ca(2+), coordinating this phosphate group, to enter the binding pocket. The, crystallographic data can be aligned with the kinetic characterisation of, the variant, showing a reduction of both, guanine affinity and turnover, rate. The presence of Ca(2+) was shown to inhibit variant 9/5 and, wild-type enzyme to nearly the same extent.

About this Structure

1CH0 is a Single protein structure of sequence from Aspergillus oryzae with CA, CL and 2GP as ligands. Active as Ribonuclease T(1), with EC number 3.1.27.3 Full crystallographic information is available from OCA.

Reference

Structural analysis of an RNase T1 variant with an altered guanine binding segment., Hoschler K, Hoier H, Hubner B, Saenger W, Orth P, Hahn U, J Mol Biol. 1999 Dec 17;294(5):1231-8. PMID:10600381

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