1qz3
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(New page: 200px<br /><applet load="1qz3" size="450" color="white" frame="true" align="right" spinBox="true" caption="1qz3, resolution 2.30Å" /> '''CRYSTAL STRUCTURE OF...)
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Revision as of 19:41, 24 November 2007
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CRYSTAL STRUCTURE OF MUTANT M211S/R215L OF CARBOXYLESTERASE EST2 COMPLEXED WITH HEXADECANESULFONATE
Overview
The reaction mechanism of the esterase 2 (EST2) from Alicyclobacillus, acidocaldarius was studied at the kinetic and structural level to shed, light on the mechanism of activity and substrate specificity increase, previously observed in its double mutant M211S/R215L. In particular, the, values of kinetic constants (k1, k(-1), k2, and k3) along with activation, energies (E1, E(-1), E2, and E3) were measured for wild type and mutant, enzyme. The previously suggested substrate-induced switch in the reaction, mechanism from kcat=k3 with a short acyl chain substrate (p-nitrophenyl, hexanoate) to kcat=k2 with a long acyl chain substrate (p-nitrophenyl, dodecanoate) was validated. The inhibition afforded by an irreversible, inhibitor (1-hexadecanesulfonyl chloride), structurally related to, p-nitrophenyl dodecanoate, was studied by kinetic analysis. Moreover the, three-dimensional structure of the double mutant bound to this inhibitor, was determined, providing essential information on the enzyme mechanism., In fact, structural analysis explained the observed substrate-induced, switch because of an inversion in the binding mode of the long acyl chain, derivatives with respect to the acyl- and alcohol-binding sites.
About this Structure
1QZ3 is a Single protein structure of sequence from Alicyclobacillus acidocaldarius with HDS as ligand. Active as Carboxylesterase, with EC number 3.1.1.1 Full crystallographic information is available from OCA.
Reference
A substrate-induced switch in the reaction mechanism of a thermophilic esterase: kinetic evidences and structural basis., De Simone G, Mandrich L, Menchise V, Giordano V, Febbraio F, Rossi M, Pedone C, Manco G, J Biol Chem. 2004 Feb 20;279(8):6815-23. Epub 2003 Nov 15. PMID:14617621
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