Catabolism of carbon skeleton of amino acids
Which of the following is not synthesised from tyrosine?
| A |
Norepinephrine |
|
| B |
Melatonin |
|
| C |
Thyroxine |
|
| D |
Dopamine |
Which of the following is not synthesised from tyrosine?
| A |
Norepinephrine |
|
| B |
Melatonin |
|
| C |
Thyroxine |
|
| D |
Dopamine |
Which of the following is derived from tyrosine ‑
| A |
Melatonin |
|
| B |
Serotonin |
|
| C |
Melanin |
|
| D |
Niacin |
Which of the following is derived from tyrosine ‑
| A |
Melatonin |
|
| B |
Serotonin |
|
| C |
Melanin |
|
| D |
Niacin |
Ans. is ‘c’ i.e., Melanin
Tyrosine is a precursor of many important compounds such as catecholamines (epinephrine, norepinephrine ), dopamine), thyroxine, triiodothryonine, melanin.
Enzyme deficient in tyrosinemia type 1 ‑
| A |
Phenylalanine hydroxylase |
|
| B |
Tyrosinase |
|
| C |
Fumarylacetoacetate hydroxylase |
|
| D |
Tyrosine transaminase |
Enzyme deficient in tyrosinemia type 1 ‑
| A |
Phenylalanine hydroxylase |
|
| B |
Tyrosinase |
|
| C |
Fumarylacetoacetate hydroxylase |
|
| D |
Tyrosine transaminase |
Tyrosinemia
It is a defect in metabolism of tyrosine. It may be of following types :-
- Tyrosinemia type-I (tyrosinosis/hepatorenal syndrome) :- It is due to defect in fumarylacetoacetate hydroxylase deficiency. Patients with chronic tyrosinosis are prone to develop cirrhosis and hepatic carcinoma. There is cabbage like odor in acute tyrosinosis.
- Tyrosinemia type – II (Richer-Hanhart syndrome) :- It is due to deficiency of tyrosine transaminase (tyrosine aminotrans-ferase).
- Neonatal tyrosinemia : – It is due to deficiency of hydroxyphenyl pyruvate hydroxylase.
