Effect of D 2 O on Uptake in Yeast. ∗

Summary

Deuterium inhibited uptake of glucose, potassium, and phosphate. Potassium uptake inhibition was probably due to the depressed rate of glucose catabolism in D₂O. Glucose and phosphate uptake inhibition was due to direct isotope effects on the transport processes. Uptake and the effects of D₂O on uptake were the same for deu-terio-glucose as for ordinary glucose. Results of experiments on the effects of D₂O on sor-bose and glucose transport indicated that these sugars enter the cell by different mechanisms. It was concluded that the immediate effects of D₂O in depressing the rates of growth and glucose catabolism were due to inhibition of glucose and phosphate uptake.

The author is indebted to Dr. J. J. Katz, of Ar-gonne National Laboratory, who generously supplied the deuterated glucose and to Mrs. L. S. Winn for skilled technical assistance.