A tetrapeptide, "x" on complete hydrolysis produced glycine (Gly), alanine (Ala), valine (Val), leucine (Leu) in equimolar proportion each. The number of tetrapeptides (sequences) possible involving each of these amino acids is:
- 32
- 24
- 8
- 16
Answer
(2) 24
Solution
Equimolar hydrolysis products each of the four different amino acids occurs exactly once in the tetrapeptide.
A peptide chain has a definite direction (N-terminal to C-terminal), so every different order of the four residues is a different tetrapeptide.
Number of sequences = 4! = 4 3 2 1 = 24
Answer: (2)