Does urea formation have a feedback inhibition mechanism Explain the Essay

Does urea formation have a feedback inhibition mechanism Explain the why or why not - Essay Example Carbomyl phosphate synthase I acts as the rate limiting enzyme in urea cycle. N-acetylglutamate allosterically activates it thus lowering its Km for protein synthesis. Carbomyl Phosphate Synthase I binds with the primary ATP molecule and converts into a vigorous conformation. It then changes into a second form by binding with N-acetylglutamate thus enhancing its own ATP affinity. As a result, a phosphate group is transferred from a subsequent ATP to the enzyme bound carbamate. This changes the carbamate to carbomyl phosphate. This happens according to the Rubio-Britton-Grisolia model. Hence, it is seen that hepatic N-acetylglutamate controls the rate of protein synthesis in the urea cycle, by regulating its rate-limiting enzyme allosterically (Das 475). Arginine does not cause feedback inhibition of Carbomyl PS-1 or OTC but stimulates the activity of acetylglutamate synthetase. However, according to Snodgrass (67), â€Å"in bacteria and fungi, arginine inhibits conversion of glutamate to acetylglutamate†. Also, only at high concentration levels, orthinine transcarbomylase and argininosuccinate synthase undergo feedback inhibition mechanism by citrulline and argininosuccinate, which are their respective