In the early 1930s, Albert Szent-Györgyi reported the interesting observation th
ID: 94057 • Letter: I
Question
In the early 1930s, Albert Szent-Györgyi reported the interesting observation that the addition of small amounts of oxaloacetate or malate to suspensions of minced pigeon breast muscle stimulated the oxygen consumption of the preparation. Surprisingly, the amount of oxygen consumed was about seven times more than the amount necessary for complete oxidation (to CO2 and H2O) of the added oxaloacetate or malate. Why did the addition of oxaloacetate or malate stimulate oxygen consumption? Why was the amount of oxygen consumed so much greater than the amount necessary to completely oxidize the added oxaloacetate or malate?
Explanation / Answer
The activity of the first two stages of cellular respiration glycolysis and TCA cycle are measured by the oxygen consumption. Addition of helps to increase the rate of TCA cycle. In the last step of TCA cycle malate is dehydrogenetated to regenerate oxaloacetate which is necessary for the entry of acetyl CoA into cycle. Thus increase in malate or oxaloacetate conc. increase the rate of cycle in forward direction. Thus the oxygen consumption rate also increased. The amount of oxygen consumed so much greater than the amount necessary to completely oxidize the added oxaloacetate or malate because the added amount of malate or oxaloacetate plays a catalytic role here. They are regenerate during the cycle where as oxygen is not. Thus more oxygen is consumed.