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

Step-by-step solution

A tetra-peptide is made of naturally occuring alanine serine glycine and valine. It is given that C -terminal amino acid is alanine and N -terminal amino acid is chiral, thus glycine can't be N -terminal amino acid as it is an achiral amino acid. Therefore possible sequence of tetra-peptide are as follows. (i) Alanine, glycine, serine, valine (ii) Alanine, glycine, valine, serine (iii) Alanine, serine, glycine, valine (iv) Alanine, valine, glycine, serine Thus it can have 4 possible sequences of the tetrapeptid