1chm
From Proteopedia
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ENZYMATIC MECHANISM OF CREATINE AMIDINOHYDROLASE AS DEDUCED FROM CRYSTAL STRUCTURES
Overview
Crystal structures of the enzyme creatine amidinohydrolase (creatinase, EC, 3.5.3.3) with two different inhibitors, the reaction product sarcosine and, the substrate creatine, bound have been analyzed by X-ray diffraction, methods. With the inhibitor carbamoyl sarcosine, two different crystal, forms at different pH values have been determined. An enzymatic mechanism, is proposed on the basis of the eight structures analyzed. The enzyme, binds substrate and inhibitor in a distorted geometry where the urea, resonance is broken. His232 is the general base and acid, and acts as a, proton shuttle. It withdraws a proton from water 377 and donates it to the, N(3) atom of the guanidinium group. OH- 377 adds to the C(1) atom of the, guanidinium group to form a urea hydrate. Proton withdrawal by His232, leads to products. The reaction product sarcosine binds to the active site, in a reverse orientation. The free enzyme was found to have a bicarbonate, bound to the active site.
About this Structure
1CHM is a Single protein structure of sequence from Pseudomonas putida with CMS as ligand. Active as Creatinase, with EC number 3.5.3.3 Full crystallographic information is available from OCA.
Reference
Enzymatic mechanism of creatine amidinohydrolase as deduced from crystal structures., Coll M, Knof SH, Ohga Y, Messerschmidt A, Huber R, Moellering H, Russmann L, Schumacher G, J Mol Biol. 1990 Jul 20;214(2):597-610. PMID:1696320
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