Studies on algal cytochromes II. : Some physical and chemical properties of further purified Petalonia cytochrome c-553

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A cytochrome c-553 was isolated from a brown alga, Petalonia fascia, and its physical and chemical properties were investigated. At liquid nitrogen temperature, the α-, β- and γ-band of this cytochrome shifted 1-2 nm to the shorter wavelength in comparison with those at room temperature. The α-band split into two peaks, 551.5 (major band) and 546.5 nm (minor band), at the low temperature. The cytochrome in high con-centration showed a shoulder at 695 nm in its oxidized state, suggesting a methionine residue to be the sixth ligand of heme iron. The molecular weight was estimated to be about 10,000 containing one mole of heme c based on analyses of gel filtration, sodium dodecyl sulfate acrylamide gel electrophoresis, amino acid composition and iron content. The isoelectric points of the ferro- and ferricytochromes were estimated to be at pH 4.1 and 4.3, respectively, by the isoelectric focusing method. The amino acid composition of this cytochrome was Lys_6, Arg_1, Asp_<15>, Thr_5, Ser_6, Glu_<11>, Pro_2, Gly_7, Ala_7, Cys_2, Val_6, Met_3, Ile_6, Leu_3, Tyr_1, Phe_3, Trp_1, with a total of 86 residues. The amino- and carboxyl-terminal sequences and four chymotryptic peptide sequences were compared with those of other cytochromes c to show that these cytochromes were homologous to one another.
日本植物生理学会の論文