Can somebody please clarify my silly doubt , when PEP (phospo enol pyruvate ) is converted into oxaloacetate by anaplerotic reaction, why krebs cycle is taking place in system. What is the importance other than oxidation of acetyl Co.A
Respected Abbas Sir
In anaplerotic reactions intermediates are not involved and it directly results the end product , than whats the role of krebs cycle.
Thank you
Although I was not familiar with this topic, my brief reading in Wikipedia explained that the purpose of anaplerotic reactions is to restore intermediates into the citric acid cycle when levels drop due to the consumption of said intermediates in other reactions. Your concern seems to be that if it is possible to go from pyruvate (not PEP) to oxaloacetate by way of the enzyme pyruvate carboxylase, then why bother with the rest of the cycle. I think the answer is that the purpose of the citric acid cycle is to generate NADH and FADH2 (etc.) to be used in the production of ATP by oxidative phosphorylation. The anaplerotic reaction of pyruvate carboxylase consumes ATP and generates no NADH:
pyruvate + ATP + HCO3- oxaloacetate + ADP + Pi.
PEP carboxylase makes malate:
PEP + HCO3- malate + Pi.
It doesn't consume any ATP, but neither does it make any ATP or NADH.
Respected Shapiro sir
Thank you very much for your valuable time spent for my question, i have realized now clearly about ATP synthesis , earlier i just focused on end product and free energy but i did not see the ATP consume in anaplerotic reaction.
Thank you for support
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