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J Bacteriol. 1965 February; 89(2): 299-305
Copyright © 1965 American Society for Microbiology. All Rights Reserved.

Synthesis of 2-Demethyl Vitamin K₂ and the Cytochrome System in Haemophilus

Department of Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky

ABSTRACT

WHITE, DAVID C. (University of Kentucky College of Medicine, Lexington). Synthesis of 2-demethyl vitamin K₂ and the cytochrome system in Haemophilus. J. Bacteriol. 89:299–305. 1965.—The synthesis of the respiratory quinone, 2-demethyl vitamin K₂, is stimulated in Haemophilus parainfluenzae under conditions which provoke the synthesis of the cytochrome system. However, the various components of the electron-transport system can be formed in different proportions. The primary flavoprotein dehydrogenases are readily dissociated from the membrane without affecting the content of membrane-bound quinone, cytochrome b₁, or the cytochrome oxidases. These dehydrogenases must be membrane-bound to function, and each can be formed at a different rate. Molar ratios of various constituents of the electron-transport chain were calculated by use of reasonable extinction coefficients for the cytochromes. The molar ratio of quinone to cytochrome c₁ goes from 40 to 3 as the quinone content increases eightfold during the growth cycle. Similarly, the molar ratio of quinone to cytochrome oxidase a₂ varies from 27 to 17, and then increases to 31 as cytochrome oxidase a₁ assumes the oxidase function. The molar ratio of quinone to cytochrome b₁ remains 14 to 1 over a sixfold increase in both components measured in a mutant where cytochrome c₁ does not obscure cytochrome b₁. A similar consistency was noted between the quinone and cytochrome b₁ formation in the hemin-requiring H. influenzae.