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1v1d
From Proteopedia
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NUCLEOPHILIC AND GENERAL ACID CATALYSIS AT PHYSIOLOGICAL PH BY A DESIGNED MINIATURE ESTERASE
Overview
A 31-residue peptide (Art-Est) was designed to catalyse the hydrolysis of, p-nitrophenyl esters through histidine catalysis on the solvent exposed, face of the alpha-helix of bovine pancreatic polypeptide. NMR spectroscopy, indicated that Art-Est adopted a stable 3-dimensional structure in, solution. Art-Est was an efficient catalyst with second order rate, constants of up to 0.050 M(-1) s(-1). The activity of Art-Est was a, consequence of the increased nucleophilicity of His-22, which had a, reduced pK(a) value of 5.5 as a consequence of its interaction with His-18, and the positively charged Arg-25 and Arg-26. Mass spectrometry and NMR, spectroscopy confirmed that the Art-Est catalysed hydrolysis of, p-nitrophenyl esters proceeded through an acyl-enzyme intermediate. A, solvent kinetic isotope effect of 1.8 indicated that the transition state, preceding the acyl intermediate was stabilised through interaction with, the protonated side-chain of His-18 and indicated a reaction mechanism, similar to that generally observed for natural esterases. The involvement, in the reaction of two histidine residues with different pK(a) values led, to a bell-shaped dependence of the reaction rate on the pH of the, solution. The catalytic behaviour of Art-Est indicated that designed, miniature enzymes can act in a transparent mechanism based fashion with, enzyme-like behaviour through the interplay of several amino acid, residues.
About this Structure
1V1D is a Single protein structure of sequence from [1]. Full crystallographic information is available from OCA.
Reference
Nucleophilic and general acid catalysis at physiological pH by a designed miniature esterase., Nicoll AJ, Allemann RK, Org Biomol Chem. 2004 Aug 7;2(15):2175-80. Epub 2004 Jul 8. PMID:15280952
Page seeded by OCA on Wed Nov 21 04:22:42 2007
