Biosynthesis of Riboflavin. The Reaction Catalyzed by 6,7-Dimethyl-8-ribityllumazine Synthase Can Proceed without Enzymatic Catalysis under Physiological Conditions<sup>†</sup>
作者:Klaus Kis、Karl Kugelbrey、Adelbert Bacher
DOI:10.1021/jo001120s
日期:2001.4.1
lumazine by condensation of 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione and 3,4-dihydroxy-2-butanone 4-phosphate is catalyzed by the enzyme, lumazine synthase. We show that the condensation reaction can proceed without enzyme catalysis in dilute aqueous solution at room temperature and neutral pH. The reaction rate is proportional to e (pH). The activation energy of the uncatalyzed reaction is E(a)
6,7-二甲基-8-ribityllumazine是维生素核黄素的生物合成前体。通过5-氨基-6-核糖基氨基-2,4(1H,3H)-嘧啶二酮和3,4-二羟基-2-丁酮4-磷酸的缩合反应,通过生物合成酶催化合成玉米素。我们表明在室温和中性pH的稀水溶液中,缩合反应可以在没有酶催化的情况下进行。反应速率与e(pH)成正比。未催化反应的活化能为E(a)= 46.3 kJ mol(-)(1)。未催化反应的区域选择性随pH和温度(65℃和pH 7.75的70%)而增加。数据表明未催化反应通过两个不同的反应途径分配。