The sequence of kassinin, a tachykinin dodecapeptide from the African frog Kassina senegalensis, was determined. A single round of Edman degradation identifies Asp as the N-terminus. A second sample of the peptide is treated with chymotrypsin. Two fragments are released with the following amino acid compositions: fragment I (Gly, Leu, Met, Val) and fragment II (Asp2,Gln, Lys, Phe, Pro, Ser, Val). Next, a third sample of the peptide is treated with trypsin, which results in two fragments with the following amino acid compositions: fragment III (Asp, Pro, Lys, Ser) and fragment IV (Asp, Gln, Gly, Leu, Met, Phe, Val2). Treatment of another sample with elastase yields a single Gly residue and three fragments—fragment V (Leu, Met), fragment VI (Asp,Lys, Pro, Ser, Val), and fragment VII, which was sequenced: Asp–Gln–Phe–Val. A fourth sample was treated with CNBr, but the dodecapeptide was not cleaved.
The sequence of kassinin, a tachykinin dodecapeptide from the African frog Kassina senegalensis, was determined. A single round of Edman degradation identifies Asp as the N-terminus. A second sample of the peptide is treated with chymotrypsin. Two fragments are released with the following amino acid compositions: fragment I (Gly, Leu, Met, Val) and fragment II (Asp2,Gln, Lys, Phe, Pro, Ser, Val). Next, a third sample of the peptide is treated with trypsin, which results in two fragments with the following amino acid compositions: fragment III (Asp, Pro, Lys, Ser) and fragment IV (Asp, Gln, Gly, Leu, Met, Phe, Val2). Treatment of another sample with elastase yields a single Gly residue and three fragments—fragment V (Leu, Met), fragment VI (Asp,Lys, Pro, Ser, Val), and fragment VII, which was sequenced: Asp–Gln–Phe–Val. A fourth sample was treated with CNBr, but the dodecapeptide was not cleaved.
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