Robinson J J, Weiner J H
Biochem J. 1981 Dec 1;199(3):473-7. doi: 10.1042/bj1990473.
A broad range of anions was shown to stimulate the maximal velocity of purified fumarate reductase isolated from the cytoplasmic membrane of Escherichia coli, while leaving the Km for fumarate unaffected. Reducing agents potentiate the effects of anions on the activity, but have no effect by themselves. Thermal stability, conformation as monitored by circular dichroism and susceptibility to the thiol reagent 5,5'-dithiobis-(2-nitrobenzoic acid) are also altered by anions. The apparent Km for succinate in the reverse reaction (succinate dehydrogenase activity) varies as a function of anion concentration, but the maximal velocity is not affected. The membrane-bound activity is not stimulated by anions and its properties closely resemble those of the purified enzyme in the presence of anions. Thus it appears that anions alter the physical and chemical properties of fumarate reductase, so that it more closely resembles the membrane-bound form.
已表明，多种阴离子可刺激从大肠杆菌细胞质膜分离出的纯化延胡索酸还原酶的最大反应速度，而延胡索酸的米氏常数（Km）不受影响。还原剂可增强阴离子对该酶活性的影响，但自身并无作用。阴离子还会改变其热稳定性、通过圆二色性监测的构象以及对硫醇试剂5,5'-二硫代双（2-硝基苯甲酸）的敏感性。在逆反应（琥珀酸脱氢酶活性）中，琥珀酸的表观米氏常数随阴离子浓度而变化，但最大反应速度不受影响。膜结合活性不受阴离子刺激，其性质与存在阴离子时纯化酶的性质极为相似。因此，阴离子似乎改变了延胡索酸还原酶的物理和化学性质，使其更类似于膜结合形式。
