Biochem= Catabolism I & II

Question 1

Describe transamination in Amino acid catabolism.

Answer 1

Transamination involves an amino group being transferred to a- ketoglutarate (a keto acid) to form glutamate.

Question 2

List the important enzyme of transamination.

Answer 2

Aminotransferase.

Question 3

What is the significance of amino acid metabolism (catabolism)

Answer 3

1. The reaction can be used to make ATP
2. To form glucose from gluconeogenesis.

Question 4

List the component that is involved in the transfer of amino groups in transamination.

Answer 4

Pyridoxal phosphate (PLP) - derivative of B6.

Question 5

Describe the transamination of Amino acids.

Answer 5

— The transamination of amino acids involves the reaction of a amino acid and a-ketogluterate to form glutamate and a ketoacid. (Ex. OAA, Pyruvate, etc.)
— Involves the transfer of a nitride group and an oxygen to form the glutamate and ketoacid.
— The presence of NADPH into NADP is involved.
— reactions are irreversible.

Question 6

Describe glutamate Synthetase reaction.

Answer 6

Glutamate + (with the presence of NH4) = glutamine.

Question 7

Th oxidative deamination of A- ketoglutarate into glutamate involves what enzyme?

Answer 7

Glutamate dehydrogenase.

Question 8

Describe oxidative deamination.

Answer 8

The process by which the nitrogen group that is transferred to AKG in the transamination process is freely converted into an ammonium ion.

Note: the ammonium ion is toxic.

Question 9

List the factors that inhibit and promote glutamate dehydrogenase.

Answer 9

Inhibit- ATP and GTP
Promote - ADP and GDP.

Question 10

State the two principal forms in which Nitrogen is transported from the muscle to the liver.

Answer 10

1. The alanine cycle
2. In the form of glutamine.

Question 11

Describe the alanine cycle.

Answer 11

1. Glutamate is formed by transamination reactions, therefore, the urea is transferred to pyruvate to form Alanine and is sent in the blood.
2. The liver picks up the alanine and transfers it back via transamination and pyruvate
3. The pyruvate is used in gluconeogenesis and the amino group is excreted in urea.

Question 12

Describe the Urea cycle.

Answer 12

CO2 + NH4+ — carbamoyl phosphate synthase I — carbamoyl phosphate — Ornithine transcarbamoylase - Citrulline — argininosuccinate synthetase (presence of aspartate and ATP) — Argininosuccinate — arginunosuccinase - Arginine (Exit of fumerate) — arginase (uptake of H2O and exit of Urea to kidney) — Ornithine

Question 13

State the effect therapy will have on metabolic disorder deficiencies.

Answer 13

1. Limit protein intake and potential build up of ammonia
2. Removal of excess ammonia
3. Replace in intermediates of the urea cycle
4. Undergo a liver transplant.

Question 14

State the deficiencies of carbomoyl phosphate synthetase and N- Acetylglutamate synthetase.

Answer 14

Hyperammonia
Encephalopathy
Respiratory alkalosis.

Question 15

State the component that activates and results in the deficiency of CPS1.

Answer 15

CPSI:
— activated by N-Acetylglutamate
— deficiency is caused by inactivity of N- Acetylglutamate synthase.

Question 16

State the two forms in which CPS1 exists in.

Answer 16

1. Neonatal/ fatal
2. Delayed onset that can arise during childhood or later.

Question 17

State the characteristics of Ornithine transcarbomoylase deficiencies.

Answer 17

1. It is the common deficiency of urea cycle enzymes.
2. Mental retardation and death can arise
3. It is found in the X chromosome
4. Occurs more in men than female.
5. Contains multiple mutations.

Question 18

State the deficiency of Argininosuccinate synthetase and lyase.

Answer 18

Citrullinemia- the inability of citrulline to combine with Aspartate resulting in an accumulation of citrulline in the blood and excreted in urine.

Question 19

State the cause of the deficiency of Argininosuccinate synthetase and lyase

Answer 19

Hyperammonemia.

Question 20

List the three distinct mutation types of Citrullinemia, an argininosuccinate synthetase and lyase deficiency.

Answer 20

— Type I- the enzyme has an altered Micheal’s constant and effected in both the kidney and liver.
— Type II- The kidney is normal and the enzyme is normal in the liver.
— Type III - the deficiency is caused by a transcription of a gene,

Question 21

State the characteristics of Arginase deficiency, arginemia.

Answer 21

1. Responsible of abnormalities central nervous system.
2. Spastic paraplegia can result
3. Type I affects only the liver
4. Type I enzyme found in cytosol and apart of formation of urea.
5. Type II enzyme found in kidney mitochondrial matrix.

Question 22

What is the deficiency of the mitochondrial Ornithine transporter?

Answer 22

Hyperammonemia, Hyperornithemia, homocitrullinemia syndrome.