Kinetics of electron transfer between soluble cytochrome c-554 and purified reaction center complex from the green sulfur bacterium Chlorobium tepidum.
Soluble cytochrome c-554 (M (r) approximately 10 kDa) is purified from the green sulfur bacterium Chlorobium tepidum. Its midpoint redox potential is determined to be +148 mV from redox titration at pH 7.0. The kinetics of cytochrome c-554 oxidation by a purified reaction center complex from the same organism were studied by flash absorption spectroscopy at room temperature, and the results indicate that the reaction partner of cytochrome c-554 is cytochrome c-551 bound to the reaction center rather than the primary donor P840. The second-order rate constant for the electron donation from cytochrome c-554 to cytochrome c-551 was estimated to be 1.7x10(7) M(-1) s(-1). The reaction rate was not significantly influenced by the ionic strength of the reaction medium.
Itoh
Masaaki
M
Department of Biology, School of Education and Division of Bioscience & Bioengineering, Graduate School of Science and Engineering, Waseda University, Nishiwaseda 1, Shinjuku, Tokyo, 169-8050, Japan, sakurai@mn.waseda.ac.jp.
Seo
Daisuke
D
Sakurai
Hidehiro
H
Sétif
Pierre
P