Cytochrome aa 3 from Methylococcus capsulatus (Bath)

Autor: Andrew K. Shiemke, Alan A. DiSpirito, Cinder L. Krema, Sean W. Jordan, James A. Zahn
Rok vydání: 1994
Předmět:
Zdroj: Archives of Microbiology. 161:258-265
ISSN: 1432-072X
0302-8933
DOI: 10.1007/bf00248702
Popis: A cytochrome aa 3-type oxidase was isolated with and without a c-type cytochrome (cytochrome c-557) from Methylococcus capsulatus Bath by ion-exchange and hydrophobic chromatography in the presence of Triton X-100. Although cytochrome c-557 was not a constitutive component of the terminal oxidase, the cytochrome c ascorbate-TMPD oxidase activity of the enzyme decreased dramatically when the ratio of cytochrome c-557 to heme a dropped below 1:3. On denaturing gels, the purified enzyme dissociated into three subunits with molecular weights of 46,000, 28,000 and 20,000. The enzyme contains two heme groups (a and a 3), absorption maximum at 422 nm in the resting state, at 445 and 601 nm in the dithionite reduced form and at 434 and 598 nm in the dithionite reduced plus CO form. Denaturing gels of the cytochrome aa 3-cytochrome c-557 complex showed the polypeptides associated with cytochrome aa 3 plus a heme c-staining subunit with a molecular weight of 37,000. The complex contains approximately two heme a, one heme c, absorption maximum at 420 nm in the resting state and at 421, 445, 522, 557 and 601 nm in the dithionite reduced form. The specific activity of the purified enzyme was 130 mol O2/min · mol heme a compared to 753 mol O2/min · mol heme a when isolated with cytochrome c-557.
Databáze: OpenAIRE
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