COMPARISON OF SPECIFICITIES OF XANTHINE-OXIDASE AND ALDEHYDE OXIDASE
COMPARISON OF SPECIFICITIES OF XANTHINE-OXIDASE AND ALDEHYDE OXIDASE
复制标题
DOI：
10.1016/0003-9861(72)90078-1
复制
发表时间：
1972-01-01
影响因子：
3.9
通讯作者：
NEIL, SM
中科院分区：
文献类型：
--
作者：
KRENITSKY, TA;ELION, GB;NEIL, SM
本研究直接比较了结构相似的羟化酶，醛氧化酶和黄嘌呤氧化酶的特异性。黄嘌呤氧化酶的各种底物的米氏常数一般低于醛氧化酶。就氧化速率而言，基本相似性是具有取代的嘧啶环结构的化合物的偏好。其中突出的差异是环取代基的数量和位置的影响。这两种酶容易氧化各种未取代和C-单取代的杂环，但只有黄嘌呤氧化酶容易氧化C-二取代的衍生物。某些N-取代，但是，增强醛氧化酶的底物活性，但显着降低它与黄嘌呤氧化酶。虽然这两种酶都喜欢氧代氨基取代基，但取代基的化学性质存在一些特异性差异。醛氧化酶，但不是黄嘌呤氧化酶，容忍6-取代嘌呤的烷基，卤代，氰基，或甲硫基，而6-羟基或6-甲氨基取代基是容忍的，只有黄嘌呤氧化酶。氧化发生的位置受取代基的化学性质和位置的影响。对于某些嘌呤，不同的位点最初被每种酶羟基化。
This study directly compares the specificities of the structurally similar hydroxylating enzymes, aldehyde oxidase and xanthine oxidase. Michaelis-Menten constants for a variety of substrates of xanthine oxidase were in general lower than those of aldehyde oxidase. With respect to the rates of oxidation, the basic similarity was a preference for compounds having a substituted pyrimidine ring structure. Outstanding among the differences were the effects of the number and position of the ring substituents. Both enzymes readily oxidized a variety of unsubstituted and C-monosubstituted heterocycles, but only xanthine oxidase readily oxidized C-disubstituted derivatives. Certain N-substitutions, however, enhanced substrate activity with aldehyde oxidase, but markedly decreased it with xanthine oxidase. Although both enzymes preferred oxo over amino substituents, there were some specificity differences with respect to the chemical nature of substituents. Aldehyde oxidase, but not xanthine oxidase, tolerated 6-substitution of purine by alkyl, halogeno, cyano, or methylthio groups, while 6-hydroxyl or 6-methylamino substituents were tolerated only by xanthine oxidase. The position at which oxidation occurred was influenced by both the chemical nature and the positions of substituents. With some purines a different site was initially hydroxylated by each enzyme.