A Yeast Cell Sugar Compartment. I. Sorbose Uptake.
ARMY MEDICAL RESEARCH LAB FORT KNOX KY
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Sorbose uptake by Saccharomyces cerevisiae was increased 40 to 60 by glucose and other fermentable sugars. Iodoacetic acid prevented the sugar effect, but cycloheximide did not. However, pretreatment of the cells with iodoacetic acid increased uptake. Neither growth nor sorbose binding were adequate to account for the increased uptake. Water space measurements showed that only 65 to 75 of available space was normally occupied by sorbose, and that addition of glucose resulted in more complete filling. Dimethylsulfoxide, which enters yeast by simple diffusion, largely filled the available water space. It is concluded that a restrictive sugar compartment prevents or slows maximum entry of sorbose into these cells metabolizable sugars and iodoacetic acid open the compartment. Author