Copper(II)-Catalyzed Transamination of Hydrophobic Pyridoxamine with Pyruvic Acid in Functionalized Bilayer Vesicles
作者:Yukito Murakami、Jun-ichi Kikuchi、Akio Nakano、Kazunari Akiyoshi、Toru Imori
DOI:10.1246/bcsj.57.1116
日期:1984.4
The copper(II)-catalyzed transamination of 2-methyl-3-hydroxy-4-aminomethyl-5-(dodecylthiomethyl)pyridine (C12SPM) with sodium pyruvate was investigated in an aqueous medium at pH 6.8, μ 0.10 (KCl), and 30.0±0.1 °C in the presence of molecular aggregates of N,N-ditetradecyl-Nα-[6-(trimethylammonio)hexanoyl]-l-alaninamide bromide (N+C5Ala2C14), N,N-ditetradecyl-Nα-[6-(trimethylammonio)hexanoyl]-l-histidinamide bromide (N+C5His2C14), or hexadecyltrimethylammonium bromide (CTAB). The reaction afforded the corresponding pyridoxal analogue (C12SPL) and alanine as the final products upon addition of edta which liberates the copper(II) ion from the coordination sites of the aldimine Schiff-base. The coordination interaction between the copper(II) ion and C12SPM, which takes place prior to the transamination, was clarified by electronic spectroscopy. The reactivity of the 2:1 (ketimine:CuII) complex was found to be much larger than that of the 1:1 complex in the molecular assemblies of N+C5Ala2C14 and CTAB, and the formation of the former species was more pronounced in the N+C5Ala2C14 vesicle. The bilayer vesicle formed with N+C5His2C14 allowed the formation of the 1:1 complex in preference to that of the 2:1 complex, and the coordination-free imidazolyl group of the amphiphile effectively catalyzed the isomerization as a general base.
在水相中,研究了铜(II)催化的2-甲基-3-羟基-4-氨基甲基-5-(十二烷基硫甲基)吡啶(C12SPM)与丙酮酸钠的转氨基化反应,反应条件为pH 6.8, μ 0.10 (KCl),温度为30.0±0.1 °C,并且存在N,N-二十四烷基-Nα-[6-(三甲铵基)己酰]-L-丙氨酸酰胺溴化物(N+C5Ala2C14)、N,N-二十四烷基-Nα-[6-(三甲铵基)己酰]-L-组氨酸酰胺溴化物(N+C5His2C14)或十六烷基三甲铵溴化物(CTAB)的分子聚集体。当加入EDTA后,反应生成相应的吡哆醇类似物(C12SPL)和丙氨酸,EDTA使铜(II)离子从醛亚胺Schiff碱的配位位点释放出来。通过电子光谱法澄清了铜(II)离子与C12SPM之间在转氨基化之前发生的配位相互作用。发现2:1(酮亚胺:CuII)复杂体的反应性远大于1:1复杂体在N+C5Ala2C14和CTAB的分子聚集中,前者在N+C5Ala2C14囊泡中更为明显。与N+C5His2C14形成的双层囊泡则更倾向于形成1:1复杂体,而非2:1复杂体,且该两亲分子的配位无关的咪唑基团有效地作为一般碱催化异构化反应。