Isolation and characterization of cytochrome b-562 from cytochrome b-c₁ comlex of the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26

A b-type cytochrome (cytochrome b-562) was highly purified from the isolated cytochrome b-c₁ complex of Rhodopseudomonas sphaeroides R-26 by treatment with sodium N-lauroyl sarcosinate (sarkosyi) and sodium thiocyanate, followed by gel filtration. The purified cytochrome b-562 was electrophoretically homogeneous, and its minimal M_r was estimated to be 16000 by SDS-polyacrylamide gel electrophoresis. It showed absorption maxima at 278, 415 and 534 nm in the oxidized form, and 428, 530 and 562 nm in the reduced form. Redox titration of this cytochrome was biphasic, giving two midpoint potentials, 55 and -100 mV, at pH 7.0. This indicates that the cytochrome is intact. Cytochrome b-562 Cytochrome b-C₁ complex Rhodopseudomonas sphaeroides.