In 1906, Harden and Young, in a series of classic studies on the fermentation of
ID: 1031680 • Letter: I
Question
In 1906, Harden and Young, in a series of classic studies on the fermentation of glucose to ethanol and CO2 by extracts of brewer’s yeast, made the following observations. 1) inorganic phosphate was essential to fermentation; when the supply of phosphate was exhausted, fermentation ceased before all the glucose was used. 2) during fermentation under these conditions, ethanol, CO2 and a hexose bisphosphate accumulated. 3) when arsenate was substituted for phosphate, no hexose bisphosphate accumulated, but the fermentation proceeded until all the glucose was converted to ethanol and CO2.
How is this reaction different from the expected GAPDH reaction? What is the consequence for the organism?
Explanation / Answer
Additon of phosphate is important to destabilize glucose which further helps in cleaving C6 and C3 of glucose to carry out the glycolysis which involve GAPDH as an enzyme.
If arsenate is used instead of phosphate, then it will also carry out the same purpose of formation of ethanol by fermentation because both As and P belong to same group and mostly have similar properties but now GAPDH will not be the enzyme as it is specific to phosphate group only.
Also since As is poisonous for an organism, thus, the accumulation of arsenate in any form leads to the death of organism.