METABOLIC STUDIES OF A FRUCTOSE-INTOLERANT YEAST BY IN-VIVO P-31-NUCLEAR MAGNETIC-RESONANCE SPECTROSCOPY

The metabolic effects of the administration of fructose to a yeast exp ressing the cDNA for rat liver ketohexokinase have been investigated b y P-31-nuclear magnetic resonance spectroscopy. Cessation of growth su ffered by the yeast on exposure to 5 and 25 mM-fructose was accompanie d by a large accumulation of fructose 1-phosphate at the expense of cy toplasmic orthophosphate and nucleoside triphosphate. Shifts in resona nces were consistent with a drop in cytoplasmic pH. Arresting growth w ith 1 mm-fructose, however, did not result in these changes, although a large accumulation of fructose 1-phosphate occurred which may have b een supported by the mobilization of polyphosphates.