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Putrescine metabolism: Enzymatic formation and non‐enzymatic isotope exchange of Δ′‐pyrroline
Author(s) -
Callery P. S.,
Nayar M. S. B.,
Geelhaar L. A.
Publication year - 1984
Publication title -
biomedical mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0306-042X
DOI - 10.1002/bms.1200110305
Subject(s) - chemistry , pyrroline , deuterium , imine , kinetic isotope effect , enamine , enzyme , enzyme catalysis , deamination , oxidative deamination , organic chemistry , catalysis , physics , quantum mechanics
The deamination of putrescine catalysed by diamine oxidase was carried out in deuterium oxide and deuterated buffers. Enamine and α,β‐unsaturated intermediates were excluded, based on the observation that deuterium was not incorporated into Δ 1 ‐pyrroline during its enzymatic formation in deuterium oxide. When the reaction mixture was buffered with phosphate, isolated Δ 1 ‐pyrroline contained two deuterium atoms at C‐3, indicating that a phosphate‐promoted, non‐enzymatic isotope exchange had occurred. Using 5,5‐dimethyl‐Δ 1 ‐pyrroline as a model compound, the nature of the non‐enzymatic deuterium exchange was studied and a bifunctional catalysis mechanism proposed. The results suggest that the choice of buffer could alter the conclusions drawn from enzyme mechanism studies involving imine‐enamine tautomerism.