Question

A peptide was cleaved into smaller fragments using chymotrypsin and CnBr. The fragments were separated by HPLC and then sequenced by Edman degradation. Determine the sequence of the original peptide from the following fragment sequences. Cleavage with chymotrypsin Cleavage with CnBr EAGPDGMECAF ECAFHR GPF CKWEAGPDGM EAAMCKW IAHTYGPFEAAM HR IAHTY -align the peptides

Answer 1

The original peptide sequence is reconstructed by aligning fragment sequences obtained from chymotrypsin and CNBr cleavages, using their specific cleavage patterns as a guide.

Step-by-step explanation:

The task involves determining the sequence of an original peptide based on fragment sequences obtained after cleavage with chymotrypsin and CNBr, followed by separation using HPLC and sequencing via Edman degradation. The sequences provided after cleavage with chymotrypsin are EAGPDGMECAF, ECAFHR, and GPF, while CNBr cleavage yielded CKWEAGPDGM, EAAMCKW, IAHTYGPFEAAM, and HR. Knowing that chymotrypsin cleaves after aromatic amino acids (F, Y, W) and CNBr cleaves at methionine (M), one can align the given peptide fragments to reconstruct the original peptide sequence. This process requires looking for overlaps and terminal correlations between the fragments considering the cleavage specificity of chymotrypsin and CNBr.

Answer 2

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