EFFECT OF PANTOTHENIC ACID ON RESPIRATORY ACTIVITY OF AEROBICALLY GROWN SACCHAROMYCES CEREVISIAE

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The respiratory activities of Saccharomyces cerevisiae requiring pantothenic acid were found to be decreased by deficiency of this acid. Respiration rate of the cells grown in a pantothenic acid-deficient medium decreased to about 1/15, and conversely hydrogen sulfide evolved at log phase was about 10 times that of the normal cells. The decrease of respiration rate was more significant than the repressed cells grown in a 5% glucose medium. These deficient cells had decreased cytochrome content and especially lacked cytochromes a+a₃ and b. Except for the activity of cytochrome oxidase, the activities of enzymes containing heme, such as cytochrome c peroxidase and catalase, were not affected. The specific activities of enzymes concerning the initial step of the biosynthesis of porphyrin were also not affected. Cytochrome oxidase, being a mitochondrial particulate enzyme, was drastically influenced by the pantothenic acid deficiency. This effect was peculiar to cytochrome oxidase and more effective than the glucose repression.