Amino Acids, Proteins and Porphyrins
Which one of the following products of protein metabolism is decreased below normal levels during the early stages of starvation?
a. During the early phases of starvation, the catabolism of proteins is at its highest level. Anabolic enzymes, which are not utilized during starvation, are degraded and their synthesis is repressed.
b. The deamination of amino acids for gluconeogenesis and keto genesis results in a negative nitrogen balance. Hence, ammonia and urea levels in the urine exceed normal values.
c. The glucose formed from gluconeogenic amino acids becomes the major source of blood glucose following depletion of liver glycogen stores.
d. Complete oxidation of this glucose, as well as the ketone bodies formed from ketogenic amino acids, leads to a relative increase in the CO2 and H2O formed from amino acid carbon skeletons.