Studies of Baker's yeast metabolism: II. The role of adenine nucleotides and inorganic phosphate in the control of respiration during alcohol oxidation

The respiratory inhibition following within 40 seconds after the addition of ethanol to a starved baker's yeast cell suspension has been studied by the analysis of intracellular adenine nucleotides and phosphate. Experiments with chemicals like glucose, 2-deoxyglucose, or glucose in the presence of iodoacetic acid have revealed that the observed respiratory inhibition is caused by the unavailability of adenosine 5'-diphosphate. By the use of a suitable phosphate trap, such as 2-deoxyglucose or glucose, it has been possible to demonstrate in the alcohol-oxidizing yeast a respiratory inhibition mediated by the lack of inorganic phosphate. A true Crabtree effect brought forth by glucose could not be demonstrated, although a net inhibition of respiratory rate has been shown by the use of 2-deoxyglucose or by glucose in the presence of iodoacetic acid. The data have been discussed in relation to the general problem of control of respiratory metabolism in intact cell systems