Enzymes as synthetic catalysts: Mechanistic and active-site considerations of natural and modified chymotrypsin
- Research Institute of Scripps Clinic, La Jolla, CA (USA) Lawrence Berkeley Lab., CA (USA)
- Texas A and M Univ., College Station (USA)
- Research Institute of Scripps Clinic, La Jolla, CA (USA)
This paper describes the mechanistic investigation of {alpha}-chymotrypsin and (Met{sub 192}-sulfoxide)-{alpha}-chymotrypsin-catalyzed peptide synthesis in a kinetically controlled process (i.e., aminolysis) and the relative stabilities of both enzymes in different conditions. Partitioning parameters for various nucleophiles (including D- and L-amino acids) competing with water for the acyl enzyme intermediate were determined. these parameters provide insights into the active-site geometries of both the native and the oxidized enzymes. {alpha}-Chymotrypsin with D-isomer selectivity in the hydrolysis of {alpha}-methyl-{alpha}-nitro esters was used for the synthesis of a D-L pseudopeptide. Molecular modeling together with kinetic results was used to explain the unusual phenomena in hydrolysis and synthesis catalyzed by the native and modified enzymes. {alpha}-Chymotrypsin methylated at the {epsilon}{sub 2}-N of the active-site histidine was shown to be an effective catalyst for peptide synthesis in the kinetically controlled process. No peptide bond hydrolysis was observed.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6651512
- Journal Information:
- Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 112:13; ISSN 0002-7863; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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