The purification of thermostable enzymes from a thermophilic hydrogen oxidizing bacterium and the development of a energy conversion system with those enzymes

点击翻译按钮获取中文摘要

In this work, we purified a ferredoxin and a hydrogenase from a thermophilic hydrogen oxidizing bacterium, Bacillus schlegelii and studied their biochemical and biophysical properties. The ferredoxin contains one [3Fe-4S] and one [4Fe-4S] cluster in a molecule. The amino acid sequence of the ferredoxin is homologous to other 7Fe type ferredoxin. This ferredoxin is active as an electron transfer agent in a reaction system for the reduction of cytochrome c consisting of NADPH, FNR, and cytochrome c. Only [3Fe-4S] cluster acts as the active site for the electron transfer reaction in the reduction of cytochrome c. This is caused by too low redox potential of the [4Fe-4S] cluster to be reduced in the reaction system.The hydrogenase purified from the bacterium is an up-take type hydrogenase that catalyzes the oxidation of hydrogen predominantly. This hydrogenase possesses 50% of the initial activity after 5 and 2.5 hours of heat treatment at 70 and 80ﾟC, respectively showing is very thermostable.