L-天冬氨酸的β-脱羧作用：一种金属螯合物催化的反应。

beta-Decarboxylation of L-aspartic acid: a metal chelate-catalyzed reaction.

作者信息

Sakkab N Y, Martell A E

出版信息

Bioinorg Chem. 1975;5(1):67-72. doi: 10.1016/s0006-3061(00)80222-7.

Abstract

beta-decarboxylation of L-aspartic acid was observed in the system, pyridoxal: L-aspartic acid:aluminum(III), 1:100:1 when heated at 80 degrees for three hours. This reaction was followed by electronic spectroscopy and showed quantitative conversion of pyridoxal to pyridoxamine indicating decarboxylation of the ketimine. alpha-Methyl-L-aspartic acid was not decarboxylated indicating the presence of the alpha-proton and prior transamination as requirements for decarboxylation. When pyridoxamine and oxalo-2-propionic acid were reacted at pD 4.60, product analysis by nmr showed the presence of pyridoxamine and alpha-ketobutyric acid, indicating hydrolysis of the decarboxylated ketimine. Decarboxylation was fast compared to spontaneous decarboxylation. A mechanism is proposed for non-enzymatic decarboxylation and the previously suggested mechanism for the inactivation of the enzyme aspartate beta-decarboxylase is discussed.

摘要

在吡哆醛

L-天冬氨酸：铝（III）比例为1:100:1的体系中，当在80摄氏度加热三小时时，观察到L-天冬氨酸的β-脱羧反应。该反应通过电子光谱监测，结果显示吡哆醛定量转化为吡哆胺，表明酮亚胺发生了脱羧反应。α-甲基-L-天冬氨酸未发生脱羧反应，这表明α-质子的存在以及转氨作用是脱羧反应的前提条件。当吡哆胺与草酰-2-丙酸在pD 4.60条件下反应时，通过核磁共振进行产物分析，结果显示存在吡哆胺和α-酮丁酸，这表明脱羧后的酮亚胺发生了水解。与自发脱羧相比，该脱羧反应速度较快。本文提出了一种非酶促脱羧反应的机制，并讨论了之前提出的天冬氨酸β-脱羧酶失活的机制。