VITAMIN K-MEDIATED ELECTRON TRANSFER IN BACILLUS SUBTILIS.

Downey, Ronald J. (University of Notre Dame, Notre Dame, Ind.). Vitamin K-mediated electron transfer in Bacillus subtilis. J. Bacteriol. 88:904-911. 1964.-Electron transfer enzymes were obtained from log-phase cells of Bacillus subtilis after aerobic and anaerobic cultivation. The cytochrome content was found to be related to oxygen tension, there being little, if any, cytochrome operative in anaerobic cells. Vitamin K levels in the two cell types did not vary as markedly. A soluble diaphorase-type flavoprotein was obtained from both types of cells which reacted with vitamin K(2), K(3), and certain dyes but not bovine cytochrome c. Almost 90% of this diaphorase activity was leached from intact protoplasts without the use of solvating agents or sonic oscillation. Electron transport particles capable of coupled phosphorylation were inhibited by light (360 mmu) or 2,3-dimercaptopropanol (BAL), whereas these had no effect on the diaphorase activity. Phosphorylation in a BAL-inhibited system was restored after addition of the soluble diaphorase from either aerobic or anaerobic cells. The results suggested that soluble flavoprotein components are linked to vitamin K in both fermentative and phosphorylative pathways, and that this segment is indispensable to aerobic and anaerobic respiration in the bacillus.