An octapeptide (Mol.wt `= 516 g`) on complete hydrolysis given glycine and alanine (Mol. Mass `= 89 g`). Alanine contributes `41.59 %` to total weight of hydrolysed product. How many number of alanine unit present in octapeptide.

Answer

3

Explanation

Molecular weight of octapeptide is `516 g//"mole"`.
Total bonds to be hydrolysed `(8-1) =7`
Total weight of `H_(2)O` added `=7 xx 18 =126 gm/"mole"`
Total weight of hydrolysed product `= 126+516 = 642 gm`.
Total weight of alanine in product `= (642 xx 41.59)/(100)=267 gm`,
Molecular weight of alanine `=89 g//"mole"`.
Number of alanine unit `= (267)/(89) =3`.