Putrescine metabolism: enzymatic formation and non-enzymatic isotope exchange of delta1-pyrroline.
The deamination of putrescine catalysed by diamine oxidase was carried out in deuterium oxide and deuterated buffers. Enamine and alpha, beta-unsaturated intermediates were excluded, based on the observation that deuterium was not incorporated into delta 1-pyrroline during its enzymatic formation in deuterium oxide. When the reaction mixture was buffered with phosphate, isolated delta 1-pyrroline contained two deuterium atoms at C-3, indicating that a phosphate-promoted, non-enzymatic isotope exchange had occurred. Using 5,5-dimethyl-delta 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 .
D006631:Amine Oxidase (Copper-Containing) / Q000378:metabolism*; D000818:Animals; D003641:Deamination; D003903:Deuterium; D066298:In Vitro Techniques; D013058:Mass Spectrometry; D011700:Putrescine / Q000378:metabolism*; D011758:Pyrroles / Q000378:metabolism*
D011758:Pyrroles; C025565:delta(1)-pyrroline; D003903:Deuterium; D006631:Amine Oxidase (Copper-Containing); D011700:Putrescine