Kinetic Mechanism of Monoamine Oxidase A

Rona R. Ramsay*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)

Abstract

Steady-state kinetic data for monoamine oxidase A in crude extracts suggest an exclusively ping-pong mechanism, in contrast to those for monoamine oxidase B, which indicate alternate mechanisms involving either a binary or ternary complex. In this study, with use of purified monoamine oxidase A, steady-state data for the inhibition by D-amphetamine of the oxidation of primary amines indicate the possibility of a ternary complex mechanism for monoamine oxidase A also. Stopped-flow studies demonstrate that the rate of reoxidation of reduced enzyme is enhanced by substrates but not by the product, 1-methyl-4-phenylpyridinium. Thus, for the A enzyme, the ternary complex with substrate, but not product, is reoxidized at a faster rate than the free, reduced enzyme. For both the A and Β forms of monoamine oxidase, the mechanism is determined by competition between alternate pathways on the basis of the relative rate constants and dissociation constants.

Original languageEnglish
Pages (from-to)4624-4629
Number of pages6
JournalBiochemistry
Volume30
Issue number18
DOIs
Publication statusPublished - 1 May 1991

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