CATALYTIC REACTIONS INVOVING AZOMETHINES .V. RATES AND EQUILIBRIA OF IMINE FORMATION WITH 3-HYDROXYPYRIDINE-4-ALDEHYDE AND AMINO ACIDS
CATALYTIC REACTIONS INVOVING AZOMETHINES .V. RATES AND EQUILIBRIA OF IMINE FORMATION WITH 3-HYDROXYPYRIDINE-4-ALDEHYDE AND AMINO ACIDS
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DOI：
10.1021/bi00877a014
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发表时间：
1965-01-01
期刊：
影响因子：
2.9
通讯作者：
BRUICE, TC
中科院分区：
文献类型：
--
作者：
FRENCH, TC;AULD, DS;BRUICE, TC
由甘氨酸、缬氨酸或谷氨酸和3-羟基吡啶-4-醛形成亚胺的过程是通过游离氨基酸对醛的三种离子形式的限速攻击进行的，然后是甲醇胺中间体的快速脱水。3-羟基的分子内催化作用在脱水步骤中显得很重要。亚胺在碱性pH下的水解通过两种途径发生，氢氧根离子和水对含有未质子化的吡啶氮和与亚胺氮氢键合的酚羟基的离子形式的攻击。pH-平衡常数曲线符合D. E. Metzler（1957，J. Am. 79，485）。
Imine formation from glycine, valine, or glutamate and 3-hydroxypyridine-4-aldehyde proceeds by rate-limiting attack of free amino acid on the three ionic forms of the aldehyde, followed by rapid dehydration of the carbinolamine intermediates. Intramolecular catalysis by the 3-hydroxy group appears to be important in the dehydration step. Hydrolysis of the imines at alkaline pH occurs by two paths, attack of hydroxide ion and water on the ionic form that contains an unprotonated pyridine nitrogen and phenolic hydroxyl hydrogen-bonded to the imine nitrogen. The pH-equilibrium constant profiles fit an equation of the kind proposed by D. E. Metzler (1957, J. Am. Chem. Soc. 79,485) for pyridoxal.