Fructose-1,6-diphosphatase, phosphofructokinase and glucose-6-phosphate dehydrogenase from fermenting and non fermenting yeasts

1. Levels of phosphofructokinase, glucose-6-phosphate dehydrogenase and fructose-1,6-diphosphatase activities have been compared in different yeasts belonging to glucose fermenting and non-fermenting groups grown in different conditions. 2. Phosphofructokinase was present in all the fermentative species tested. On the contrary its level was not measurable in any of the aerobic yeasts tested with the exception of Pichia species. 3. No significant variations were observed in the values of glucose-6-phosphate dehydrogenase from the two groups of yeasts. 4. The synthesis of fructose-1,6-diphosphatase was repressed in both groups, by growth in sugar carbon sources. However, a remarkable difference in the sensitivity of the fructose-1,6-diphosphatase from both groups towards inhibition by AMP was observed. The enzyme from all fermentative yeasts tested showed a strong inhibition by AMP (1 mM producing about 80% inhibition) while the enzyme from aerobic yeasts showed different responses, inhibition ranging from 10% in Rhodotorula and Sporobolomyces, to 90% in Pichia