Characterization and from Two Strains ofAmino Acid Sequences of Cytochromes c 6 the Green Alga

redox potential of +355 mV at pH 7.0. The absorption spectra of both cytochromes c6 showed 4 mftxima in reduced form, and2 maxima and a weak peak at 695 nm in oxidized form. The pyridine ferrohemochrome spectra indicated that their prosthetic group was heme c. These physicochemical properties were similar to those of other algal cytochromes c6. The amino acids (88 residues) of CK5cyc6 and CK22cyc6 were sequenced and the sequence motif -CXXCH-, which is typical of the heme-binding site of e-type cyto ¢hrome, was clearly confirmed in both cytochromes. Twenty-six amino acid residues were substituted, and the similarity score of