1V1D: Nucleophilic and General Acid Catalysis at Physiological pH by a Designed Miniature Esterase

Citation:
Abstract
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.
PDB ID: 1V1DDownload
MMDB ID: 32765
PDB Deposition Date: 2004/4/14
Updated in MMDB: 2007/10
Experimental Method:
solution nmr
Similar Structures:
Biological Unit for 1V1D: monomeric; determined by author
Molecular Components in 1V1D
Label Count Molecule
Protein (1 molecule)
1
Pancreatic Hormone(Gene symbol: PPY)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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