Ornithine transcarbamylase catalyzes the reaction between the substrates ornithine and carbamoyl phosphate to form citrulline and phosphate. This process occurs primarily in the hepatic mitochondria, and to a lesser extent in the mitochondria of the renal cells.

Ornithine transcarbamylase catalyzes the reaction between the substrates ornithine and carbamoyl phosphate to form citrulline and phosphate. This process occurs primarily in the hepatic mitochondria, and to a lesser extent in the mitochondria of the renal cells.

The correct answer is "glutamate dehydrogenase." Glutamate is the only amino acid that has an enzyme that removes its amino group as ammonia, rather than just transferring the amino group to a α-keto acid and forming a new amino acid. The transfer of amino groups, which may form glutamate, is performed by aminotransferases that require pyridoxal-5’-phosphate as a cofactor. Cathepsins are a type of proteases contained in lysosomes, and they break down proteins into amino acids rather than metabolize the amino acids themselves. Carbamoyl phosphate synthase is not involved in deamination, but rather condenses ammonia with bicarbonate to enter the urea cycle.

Aminotransferases (transaminases) catalyze the conversion of an amino acid to an -keto acid. To do so, they utilize a pyridoxyl phosphate coenzyme, which mediates the transfer of the amino group, leaving a ketone functional group next to the carboxyl group. This -keto acid is the product. Since the amino group in an amino acid is attached to the alpha carbon, it will not be a -keto acid. Some of the other answer choices give intermediates of the reaction mechanism, not the product.

Aminotransferases (transaminases) catalyze the conversion of an amino acid to an -keto acid. To do so, they utilize a pyridoxyl phosphate coenzyme, which mediates the transfer of the amino group, leaving a ketone functional group next to the carboxyl group. This -keto acid is the product. Since the amino group in an amino acid is attached to the alpha carbon, it will not be a -keto acid. Some of the other answer choices give intermediates of the reaction mechanism, not the product.

The correct answer is "glutamate dehydrogenase." Glutamate is the only amino acid that has an enzyme that removes its amino group as ammonia, rather than just transferring the amino group to a α-keto acid and forming a new amino acid. The transfer of amino groups, which may form glutamate, is performed by aminotransferases that require pyridoxal-5’-phosphate as a cofactor. Cathepsins are a type of proteases contained in lysosomes, and they break down proteins into amino acids rather than metabolize the amino acids themselves. Carbamoyl phosphate synthase is not involved in deamination, but rather condenses ammonia with bicarbonate to enter the urea cycle.

The urea cycle is vital to the excretion of ammonia, a harmful byproduct of amino acid breakdown. Via a series of enzymatic changes, ammonia is converted to urea, which can be excreted into the urine.

The urea cycle is vital to the excretion of ammonia, a harmful byproduct of amino acid breakdown. Via a series of enzymatic changes, ammonia is converted to urea, which can be excreted into the urine.

The urea cycle occurs primarily in the liver, and to a lesser extent in renal cells. There is no urea conversion performed by the small intestine.

When proteins and amino acids are broken down in the body, ammonium is created as a byproduct. Ammonium is dangerous when it remains free in the human body, so something must be done to get rid of it. The major route of removal of ammonium by the body is via urea synthesis in the liver. Urea can then be excreted in urine.