J. Biol. Chem., Vol. 261, Issue 2, 548-551, Jan, 1986
Purification and properties of a diheme cytochrome b561 of the Escherichia coli respiratory chain
H Murakami, K Kita and Y Anraku
A new b-type cytochrome, cytochrome b561 (Murakami, H., Kita, K., Oya, H.,
and Anraku, Y. (1984) Mol. Gen. Genet. 196, 1-5) was purified to near
homogeneity from the cytochrome b561-amplified Escherichia coli K12 strain
HM204/pAM5029. The purified cytochrome b561 was a single polypeptide with a
molecular weight of 18,000, determined by sodium dodecyl
sulfate-polyacrylamide gel electrophoresis. Its isoelectric point was
determined to be 9.6. The difference spectrum of the cytochrome at 77 K
shows a major alpha-absorption peak at 561 nm and a minor peak at 555 nm.
The absolute spectrum at room temperature of the oxidized form of the
cytochrome had an absorption peak at 414 nm, and that of the reduced form
had peaks at 562, 530, and 428 nm. The oxidation-reduction potential of the
cytochrome was estimated to be +20 mV. The cytochrome contained 91.2 nmol
of heme/mg of protein, showing that it was a cytoplasmic membrane-bound,
b-type diheme cytochrome.