Miki K, Lin E C
J Bacteriol. 1973 May;114(2):767-71. doi: 10.1128/jb.114.2.767-771.1973.
Anaerobic growth of Escherichia coli on glycerol as carbon source and fumarate as hydrogen acceptor results in the induction of both anaerobic sn-glycerol-3-phosphate (G3P) dehydrogenase and fumarate reductase. In previous studies, the G3P dehydrogenase was measured by the G3P-dependent reduction of a tetrazolium dye mediated by phenazine methosulfate in the presence of flavine mononucleotide and flavine adenine dinucleotide, and fumarate reductase was measured by the fumarate-dependent oxidation of reduced flavine mononucleotide. Results from the present study indicate that these two enzymes actually constitute a functional complex which is sedimentable at 200,000 x g in 2 h and which can catalyze the dehydrogenation of G3P at the expense of fumarate without any added cofactor. This coupling activity is not constituted by simply mixing an extract containing anaerobic G3P dehydrogenase with another extract containing fumarate reductase. Additional evidence for an organized complex is provided by the high degree of sensitivity of the coupled reaction to low concentrations of the detergents Triton X-100 and Emasol 1130 in comparison with the individual activities of the two component enzymes measured with the aid of artificial cofactors.
以甘油作为碳源、富马酸作为氢受体时，大肠杆菌的厌氧生长会导致厌氧的sn-甘油-3-磷酸（G3P）脱氢酶和富马酸还原酶的诱导。在先前的研究中，G3P脱氢酶是通过在黄素单核苷酸和黄素腺嘌呤二核苷酸存在下，由吩嗪硫酸甲酯介导的G3P依赖的四唑染料还原进行测定的，而富马酸还原酶是通过还原型黄素单核苷酸的富马酸依赖的氧化进行测定的。本研究结果表明，这两种酶实际上构成了一种功能复合体，该复合体在200,000×g离心2小时后可沉淀，并且在不添加任何辅因子的情况下，能够以富马酸为代价催化G3P的脱氢反应。这种偶联活性不是简单地将含有厌氧G3P脱氢酶的提取物与另一种含有富马酸还原酶的提取物混合而成的。与借助人工辅因子测定的两种组成酶的个体活性相比，偶联反应对低浓度去污剂Triton X-100和Emasol 1130的高度敏感性为有序复合体提供了额外的证据。
