a.A nonapeptide was determined to have the following amino acid composition: (Lys)2, (Gly) 2, (Phe) 2, His, Leu, Met.
b.The native peptide was incubated with 1-fluoro-2,4-dinitrobenzene (FDNB) and then hydrolyzed; 2,4-dinitrophenylhistidine was identified.
c.When the native peptide was exposed to cyanogen bromide (CNBr), an octapeptide and free glycine were recovered.
d.Incubation of the native peptide with trypsin gave a pentapeptide, a tripeptide, and free Lys. 2,4-Dinitrophenyl-histidine was recovered from the pentapeptide, and 2,4-dinitrophenylphenylalanine was recovered from the tripeptide.
e.Digestion with the enzyme pepsin produced a dipeptide, a tripeptide, and a tetrapeptide. The tetrapeptide was composed of (Lys) 2, Phe, and Gly.