IRON-SULFUR CLUSTERS OF HYDROGENASE-I AND HYDROGENASE-II OF CLOSTRIDIUM-PASTEURIANUM
IRON-SULFUR CLUSTERS OF HYDROGENASE-I AND HYDROGENASE-II OF CLOSTRIDIUM-PASTEURIANUM
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DOI：
10.1073/pnas.86.13.4932
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发表时间：
1989-07-01
影响因子：
11.1
通讯作者：
HOWARD, JB
中科院分区：
文献类型：
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作者：
ADAMS, MWW;ECCLESTON, E;HOWARD, JB
铁和酸不稳定的硫化物含量和电子顺磁共振（EPR）性质的氢化酶I（双向）和氢化酶II（摄取）的巴氏梭菌（菌株W5）已确定的基础上定量氨基酸分析。铁和酸不稳定的硫化物值分别为每分子氢化酶I约20和18个原子，每分子氢化酶II约14和11个原子。这些量显著大于先前报道的值，其依赖于通过比色测定法测定的蛋白质浓度。氧化的氢化酶表现出不寻常的EPR信号，起源于一种新类型的铁硫中心称为hydrogenae或H簇，共价结合的抑制剂CO。这EPR信号表示约一个未配对的电子每个分子在每个酶与和没有绑定CO，这是一致的存在下，一个氧化的H簇（S = 1/2）每个酶分子。这两种酶还含有铁氧还蛋白型四铁中心或F簇。在还原形式的氢化酶I和氢化酶II中观察到的F簇的EPR信号分别占每个分子约4个和1个未配对电子。我们得出结论，从铁的测定和EPR reusults，再加上重新评估先前的光谱数据，在这两个氢化酶的H簇可能包括6个铁原子。这两个氢化酶的机制模型，占他们的集群组合物和催化活性的显着差异。
The iron and acid-labile sulfide contents and the electron paramagnetic resonance (EPR) properties of hydrogenase I (bidirectional) and hydrogenase II (uptake) of Clostridium pasteurianum (strain W5) have been determined on the basis of quantitative amino acid analyses. The iron and acid-labile sulfide values are approximately 20 and 18 atoms per molecule of hydrogenase I and 14 and 11 atoms per molecule of hydrogenase II, respectively. These amounts are substantially greater than previously reported values, which relied on protein concentration determined by colorimetric assay. The oxidized hydrogenases exhibit unusual EPR signals that originate from a novel type of iron-sulfur center termed the hydrogenae or H cluster, which covalently binds the inhibitor CO. This EPR signal represents approximately one unpaired electron per molecule in each enzyme with and without bound CO, which is consistent with the presence of one oxidized H cluster (S = 1/2) per enzyme molecule. The two enzymes also contain ferredoxin-type four-iron centers or F clusters. The EPR signals from the F clusters observed in the reduced forms of hydrogenase I and hydrogenase II account for approximately four and one unpaired electron per molecule, respectively. We conclude from the iron determinations and the EPR resusults, together with a reevaluation of prvious spectroscopic data, that in both hydrogenases the H cluster probably comprises six iron atoms. Mechanistic models of the two hydrogenases are presented that account for their cluster compositions and the dramatic differences in their catalytic activities.