KROK 1 2007 – Question 19 · KROK (Medicine) · Biological Chemistry
Ammonia is a very toxic substance, especially for nervous system. What substance takes the most active part in ammonia detoxication in brain tissues?
- A. Proline
- B. Alanine
- C. Lysine
- D. Histidine
- E. Glutamic acid
Hint
The brain has no effective urea cycle, so it traps ammonia by an ATP-dependent amidation of a side-chain carboxyl group; ask which of the listed amino acids is abundant in nervous tissue and has such a group available.
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