Babalola O, Cancedda R, Luzzatto L
Proc Natl Acad Sci U S A. 1972 Apr;69(4):946-50. doi: 10.1073/pnas.69.4.946.
The A(-) type of glucose 6-phosphate dehydrogenase (EC 1.1.1.49) has been isolated from human erythrocytes deficient in this enzyme. The specific activity of the purified protein is similar to that previously reported for the enzyme isolated from normal, nondeficient erythrocytes. During the purification procedure, a portion of the A(-) enzyme converts spontaneously, from the native "fraction I", to a "fraction II" having different kinetic and chromatographic properties. The conversion of fraction I to II can be reproduced freely by treatment with iodosobenzoate, and fraction II can be converted back to fraction I by treatment with dithioglycol. We suggest that fraction II is an enzyme species in which one or more sulfhydryl groups have been oxidized to disulfide(s). The tendency to oxidation appears to be a property specific to the A(-) variant and may represent the basis for its rapid rate of inactivation and consequent deficiency in vivo.
已从缺乏该酶的人红细胞中分离出A(-)型葡萄糖6-磷酸脱氢酶（EC 1.1.1.49）。纯化蛋白的比活性与先前报道的从正常、不缺乏该酶的红细胞中分离出的酶相似。在纯化过程中，一部分A(-)酶会自发地从天然的“组分I”转变为具有不同动力学和色谱性质的“组分II”。通过用碘代苯甲酸处理可以自由再现组分I向组分II的转变，并且通过用二硫代二醇处理可以将组分II转变回组分I。我们认为组分II是一种酶形式，其中一个或多个巯基已被氧化为二硫键。氧化倾向似乎是A(-)变体特有的性质，可能是其体内快速失活和由此导致缺乏的基础。
