Kinetic studies on the oxidation of cytochrome b(5) Phe35 mutants with cytochrome c, plastocyanin and inorganic complexes.

Ping Yao, Yun-Hua Wang, Bing-Yun Sun, Yi Xie, Shun Hirota, Osamu Yamauchi, Zhong-Xian Huang

Index: J. Biol. Inorg. Chem. 7(4-5) , 375-83, (2002)

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Abstract

To illustrate the functions of the aromatic residue Phe35 of cytochrome b(5) and to give further insight into the roles of the Phe35-containing hydrophobic patch and/or aromatic channel of cytochrome b(5), we studied electron transfer reactions of cytochrome b(5) and its Phe35Tyr and Phe35Leu variants with cytochrome c, with the wild-type and Tyr83Phe and Tyr83Leu variants of plastocyanin, and with the inorganic complexes [Fe(EDTA)](-), [Fe(CDTA)](-) and [Ru(NH(3))(6)](3+). The changes at Phe35 of cytochrome b(5) and Tyr83 of plastocyanin do not affect the second-order rate constants for the electron transfer reactions. These results show that the invariant aromatic residues and aromatic patch/channel are not essential for electron transfer in these systems.