In 1906, Harden and Young, in a series of classic studies on the fermentation of glucose to ethanol and CO 2 by extracts of brew
er'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. <u>Since enzymatic reactions take place by forming enzyme-substrate complexes</u>, absence of the inorganic phosphate substrate ; stops the conversion and progress of fermentation .
