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Title: cap alpha. -deuterium and carbon-13 isotope effects for methyl transfer catalyzed by catechol O-methyltransferase. S/sub N/2-like transition state

Journal Article · · J. Am. Chem. Soc.; (United States)
DOI:https://doi.org/10.1021/ja00509a052· OSTI ID:5776917

The rate at near saturation of methylation of 3,4-dihydroxyacetophenone by S-adenosyl-L-methionine, catalyzed by rat-liver catechol O-methyltransferase at pH 7.58 and 37.00 +- 0.05/sup 0/C, is increased by deuteration of the methyl group (V/sub CH/sub 3///V/sub CD/sub 3// = 0.83 +- 0.05) and decreased by introduction of /sup 13/C to the methyl group (V/sub 12//V/sub 13/ = 1.09 +- 0.05). This shows the rate-determining step to be transfer of the methyl group, with an S/sub N/2-like transition state in which the methyl is located symmetrically and tightly between leaving group and nucleophile.

Research Organization:
Univ. of Kansas, Lawrence
OSTI ID:
5776917
Journal Information:
J. Am. Chem. Soc.; (United States), Vol. 101:15
Country of Publication:
United States
Language:
English