A tetrapeptide is made of naturally occuring alanine, serine, glycine and valine. If the C -terminal amino acid is alanine and N -terminal amino acid is chiral, the number of possible sequence of the tetrapeptide is

Step-by-step solution

Since glycine (gly) is achiral, alanine (Ala) is the C-terminal amino acid, therefore N -terminal amino acid can be valine (val) or serine (ser). In the view of these condition, the following four sequences for the tetrapeptide is possible. (i) Val-gly-Ser-Ala (ii) Val-Ser-gly-Ala (iii) Ser-gly-Val-Ala (iv) Ser-Val-gly-Ala