Callery P S, Nayar M S, Geelhaar L A
Biomed Mass Spectrom. 1984 Mar;11(3):118-20. doi: 10.1002/bms.1200110305.
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 .
由二胺氧化酶催化的腐胺脱氨反应在氧化氘和氘代缓冲液中进行。基于在氧化氘中酶促形成δ1-脯氨酸的过程中氘未掺入其中的观察结果，排除了烯胺和α,β-不饱和中间体。当反应混合物用磷酸盐缓冲时，分离出的δ1-脯氨酸在C-3处含有两个氘原子，这表明发生了磷酸盐促进的非酶促同位素交换。以5,5-二甲基-δ1-脯氨酸为模型化合物，研究了非酶促氘交换的性质并提出了双功能催化机制。结果表明，缓冲液的选择可能会改变从涉及亚胺-烯胺互变异构的酶机制研究中得出的结论。
