1orb
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(New page: 200px<br /><applet load="1orb" size="450" color="white" frame="true" align="right" spinBox="true" caption="1orb, resolution 2.0Å" /> '''ACTIVE SITE STRUCTURA...)
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Revision as of 21:00, 20 November 2007
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ACTIVE SITE STRUCTURAL FEATURES FOR CHEMICALLY MODIFIED FORMS OF RHODANESE
Overview
In the course of the reaction catalyzed by rhodanese, the enzyme cycles, between two catalytic intermediates, the sulfur-free and the, sulfur-substituted (persulfide-containing) forms. The crystal structure of, sulfur-free rhodanese, which was prepared in solution and then, crystallized, is highly similar to that of sulfur-substituted enzyme. The, inactivation of sulfur-free rhodanese with a small molar excess of, hydrogen peroxide relies essentially on a modification limited to the, active site, consisting of the oxidation of the essential sulfhydryl to, sulfenyl group (-S-OH). Upon reaction of the sulfur-free enzyme with, monoiodoacetate in the crystal, the Cys-247 side chain with the bound, carboxymethyl group is forced into a conformation that allows favorable, interactions of the carboxylate with the four peptide NH groups that, participate in hydrogen bonding interactions with the transferable sulfur, atom of the persulfide group in the sulfur-substituted rhodanese. It is, concluded that active site-specific chemical modifications of sulfur-free, rhodanese do not lead to significant changes of the protein structure, consistent with a high degree of similarity of the structures of the, sulfur-free and sulfur-substituted forms of the enzyme both in solution, and in the crystal.
About this Structure
1ORB is a Single protein structure of sequence from Bos taurus with ACT as ligand. Active as Thiosulfate sulfurtransferase, with EC number 2.8.1.1 Full crystallographic information is available from OCA.
Reference
Active site structural features for chemically modified forms of rhodanese., Gliubich F, Gazerro M, Zanotti G, Delbono S, Bombieri G, Berni R, J Biol Chem. 1996 Aug 30;271(35):21054-61. PMID:8702871
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