7a nonanyl peptide 9 amino acids was isolated and gave an a

+ 7a nonanyl peptide (9 amino acids) was isolated and gave an amino acid composition of Pro, Glu, His, Lys, Met, Ser, Thr, Phe, Val? Carboxypeptidase A did not leave it N-terminal analysis gave a Val Treatment with trypsin gave two peptides whose amino acid composition is (Lys, Ser, Phe, Val) and (Pro, His, Met, Glu, Thr). Cyanogen Bromide digestion gave two fragments (Pro, His) and (Lys, Thr, Glu, Ser, Met, Val, Phe) Endopeptidase from V8 Staphylcoccus aurens also gave two peptides (Pro, His, Thr, Met) and (Lys, Ser, Phe, Val, Glu). Chymotrypsin gives two peptides After partial acid hydrolysis a fragment containing only His and Pro was subject to one round of Edman degradation which yielded PTH-His. From the above data derive the amino acid sequence and show all cleavage sites.

Solution

Here it is a peptide with 9 aminoacids (1-2-3-4-5-6-7-8-9)

The sequence is Val-Phe-Ser-Lys-Thr-Glu-Met-His-Pro

N-terminal analyis gaves Val.Thus 1 is Val.

Trypsin cleves Lys, so got 2 fragments it is Lys,Ser, Phe, Val and Pro, His, Met, Glu, Thr

Cyanogen bromide cleaves C-terminal Methionine residue, anything attatched with NH2 side of Met remain attatched.

Chymotrypsin cleaves at C terminal of Phenylalanine (Phe), methionine (Met), tyrosine (Tyr), and tryptophan (Trp).