Purification and characterization of two soluble cytochromes from the alkalophile Bacillus firmus RAB |
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| Authors: | M W Davidson K A Gray D B Knaff T A Krulwich |
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| Institution: | Department of Biochemistry, Mount Sinai School of Medicine, City University of New York, NY 10029. |
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| Abstract: | A soluble cytochrome c and soluble cytochrome b were purified from the alkalophilic Bacillus firmus RAB. The cytochrome c, with an alpha band at 552 nm, had an apparent molecular weight of 16,500 and was acidic, with a pI of 3.4. At both pH 7.0 and 8.3, the midpoint potential of c-552 was +66 mV. Above pH 8.3, the cytochrome exhibited a pH-dependent decrease in midpoint potential. This property, among others, distinguished the cytochrome c-552 from other membrane-associated c-type cytochromes. The soluble cytochrome b, with an alpha band maximum at 558 nm, had a molecular weight of approx. 15,500 and was also an acidic protein, with a pI of 3.07. It exhibited a pH-independent midpoint potential of +28 mV. |
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