A nonapeptide was determined to have the following amino acid composition: (Lys)2, (Gly) 2, (Phe) 2, His, Leu, Met. The native peptide was incubated with 1-fluoro-2,4-dinitrobenzene (FDNB) and then hydrolyzed; 2,4-dinitrophenylhistidine was identified by HPLC. When the native peptide was exposed to cyanogen bromide (CNBr), an octapeptide and free glycine were recovered. 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. Digestion with the enzyme pepsin produced a dipeptide, a tripeptide, and a tetrapeptide. The tetrapeptide was composed of (Lys) 2, Phe, and Gly. The native sequence was determined to be:
A) Gly-Phe-Lys-Lys-Gly-Leu-Met-Phe-His. B) His-Leu-Gly-Lys-Lys-Phe-Phe-Gly-Met. C) His-Leu-Phe-Gly-Lys-Lys-Phe-Met-Gly. D) His-Phe-Leu-Gly-Lys-Lys-Phe-Met-Gly. E) Met-Leu-Phe-Lys-Phe-Gly-Gly-Lys-His.