Putrescine metabolism: Enzymatic formation and non-enzymatic isotope exchange of Δ′-pyrroline
✍ Scribed by P. S. Callery; M. S. B. Nayar; L. A. Geelhaar
- Book ID
- 101757593
- Publisher
- John Wiley and Sons
- Year
- 1984
- Tongue
- English
- Weight
- 257 KB
- Volume
- 11
- Category
- Article
- ISSN
- 1076-5174
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✦ Synopsis
The deamination of putrescine catalysed by diamine oxidase was carried out in deuterium oxide and deuterated buffers. Enamine and a,P-unsaturated intermediates were excluded, based on the observation that deuterium was not incorporated into A'-pyrroline during its enzymatic formation in deuterium oxide. When the reaction mixture was buffered with phosphate, isolated A'-pyrroline contained two deuterium atoms at C-3, indicating that a phosphate-promoted, non-enzymatic isotope exchange had occurred. Using 5,5-dimethyl-A1-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.