1v1d
Nucleophilic and General Acid Catalysis at Physiological pH by a Designed Miniature Esterase
Structural highlights
FunctionPAHO_BOVIN Pancreatic hormone is synthesized in pancreatic islets of Langerhans and acts as a regulator of pancreatic and gastrointestinal functions. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedA 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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
| ||||||||||||||||||
