Terlesky K C, Ferry J G
Department of Anaerobic Microbiology, Virginia Polytechnic Institute and State University, Blacksburg 24061.
J Biol Chem. 1988 Mar 25;263(9):4080-2.
A ferredoxin, which functions as an electron acceptor for the CO dehydrogenase complex from Methanosarcina thermophila, was purified from acetate-grown cells. It was isolated as a trimer having a native molecular weight of approximately 16,400 and monomer molecular weight of 4,888 calculated from the amino acid composition. The ferredoxin contained 2.80 +/- 0.56 Fe atoms and 1.98 +/- 0.12 acid-labile sulfide. UV-visible absorption maxima were 395 and 295 nm with monomeric extinction coefficients of epsilon 395 = 12,800 M-1 cm-1 and epsilon 295 = 14,460 M-1 cm-1. The A395/A295 ratio ranged from 0.80 to 0.88. There were 5 cysteines per monomer but no methionine, histidine, arginine, or aromatic amino acids. The N-terminal amino acid sequence showed a 4-cysteine cluster with potential to coordinate a Fe:S center. The protein was stable for 30 min at 70 degrees C, but denatured during incubation at 85 degrees C.
从嗜热甲烷八叠球菌的乙酸盐培养细胞中纯化出一种铁氧化还原蛋白，它作为一氧化碳脱氢酶复合物的电子受体发挥作用。该蛋白以三聚体形式分离得到，其天然分子量约为16,400，根据氨基酸组成计算，单体分子量为4,888。该铁氧化还原蛋白含有2.80±0.56个铁原子和1.98±0.12个酸不稳定硫化物。紫外可见吸收峰分别位于395和295nm处，单体的消光系数为ε395 = 12,800 M-1 cm-1和ε295 = 14,460 M-1 cm-1。A395/A295比值在0.80至0.88之间。每个单体含有5个半胱氨酸，但不含甲硫氨酸、组氨酸、精氨酸或芳香族氨基酸。N端氨基酸序列显示有一个4个半胱氨酸的簇，有可能配位一个铁硫中心。该蛋白在70℃下30分钟内稳定，但在85℃孵育时变性。
