Hedderich R, Albracht S P, Linder D, Koch J, Thauer R K
Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität Marburg, Germany.
FEBS Lett. 1992 Feb 17;298(1):65-8. doi: 10.1016/0014-5793(92)80023-a.
The methylviologen-reducing hydrogenase operon of Methanobacterium thermoautotrophicum contains an open reading frame, mvhB, the product of which was predicted to have a molecular weight of 44 kDa and to contain as many as 48 iron atoms in 12 [4Fe-4S] clusters, and was therefore suggested to be a polyferredoxin. We have now, for the first time, isolated this polyferredoxin. Its identity with the mvhB gene product was evidenced by a comparison of the N-terminal amino acid sequence. The dark-brown protein of apparent molecular weight 44 kDa was found to contain 53 mol Fe and 43 mol acid-labile sulfur per mol. The UV/visible spectrum showed two maxima at 280 nm and 390 nm, and a shoulder at 308 nm. The A390/A280 ratio was 0.73. The molar extinction coefficient at 390 nm was 170,000 M-1.cm-1. In the dithionite reduced state the protein displayed an EPR spectrum like that of [4Fe-4S] clusters. The results indicate that the mvhB gene product is indeed a polyferredoxin.
嗜热自养甲烷杆菌的甲基紫精还原氢化酶操纵子含有一个开放阅读框mvhB，预计其产物分子量为44 kDa，在12个[4Fe-4S]簇中含有多达48个铁原子，因此被认为是一种多铁氧化还原蛋白。我们现在首次分离出了这种多铁氧化还原蛋白。通过对N端氨基酸序列的比较，证实了它与mvhB基因产物的一致性。发现表观分子量为44 kDa的深棕色蛋白每摩尔含有53摩尔铁和43摩尔酸不稳定硫。紫外/可见光谱在280 nm和390 nm处有两个最大值，在308 nm处有一个肩峰。A390/A280比值为0.73。390 nm处的摩尔消光系数为170,000 M-1.cm-1。在连二亚硫酸盐还原状态下，该蛋白显示出与[4Fe-4S]簇类似的电子顺磁共振谱。结果表明，mvhB基因产物确实是一种多铁氧化还原蛋白。
