Question

In a laboratory Rat, we are undertaking a number of metabolic studies regarding the etabolism of carbohydrates using "C radio-labeled glucose. However when we take blood from the rat we find the presence of very high concentrations of 'C radio-labeled Alanine. From your understanding of biochemistry illustrate, with structures, AND the state most plausible process that caused the generation of our radioactivity seen in the blood. (10 marks)

Answer 1

4.4 It is due to glucose-alanine cycle. This cycle is used primarily as a mechanism for skeletal muscle to eliminate nitrogen while replenishing its energy supply. Glucose oxidation produces pyruvate which can undergo transamination to alanine. this reaction is catalyzed by alanine transaminase (ALT). During the period of fasting, skeletal muscle protein is degraded for the energy value of the amino acid carbons and alanine is a major amino acid in the protein. The alanine then enters the bloodstream and is transported to the liver.

lvcdse vcose piate ALT lanin Muscle cel