In 1906, Harden and Young, in a series of classic studies on the fermentation of glucose to ethanol and CO 2 by extracts of brewer's yeast, made the observations inorganic phosphate was essential to fermentation; when the supply of phosphate was exhausted, fermentation ceased before all the glucose was used; during fermentation under these conditions, ethanol, CO 2 , and a sugar phosphate accumulated; when arsenate was substituted for phosphate, no sugar phosphate accumulated, but the fermentation proceeded until all the glucose was converted to ethanol and CO 2 . Which enzyme of glycolysis requires inorganic phosphate and, therefore, stops when no phosphate is available

The enzyme is Glyceraldehyde-3-phosphate-dehydrogenase. (GAPDH). It is the enzyme that converts Glyceraldehyde-3-phosphate to D-glycerate 1,3-bisphosphate; the sixth Glycolytic pathway for breaking down glucose to ethanol, C02 in Glycolysis. This enzyme requires inorganic phosphate as substrate for the catalytic reaction to proceed. Since enzymatic reactions take place by forming enzyme-substrate complexes, absence of the inorganic phosphate substrate ; stops the conversion and progress of fermentation .