57 An octapeptide was determined to have the following amino

Last updated: 4/12/2023

57 An octapeptide was determined to have the following amino acid composition Lys 2 Phe 2 Gly 1 His 1 Leu 1 Met 1 The native peptide was run through one cycle of the Edman degradation and the PTH leucine derivative was identified by HPLC When the native peptide was exposed to cyanogen bromide CNBr a heptapeptide and free glycine were recovered Incubation of the native protein with trypsin gave a tetrapeptide a tripeptide and free lysine The peptides were separated and each run through one cycle of the Edman degradation The tetrapeptide yielded the PTH leucine derivative and the tripeptide yielded the PTH phenylalanine derivative Incubation of the native protein with pepsin produced a dipeptide and two tripeptides The amino acid composition of the tripeptides not the order were determined to be Phe Gly Met and Phe Lys Lys What is the sequence of the octapeptide Specificities BrCN Trypsin Pepsin of Proteases cuts at the C terminal side of Met cuts at the C terminal side of Lys or Arg cuts at the N terminal side of Phe Trp or Tyr A His Phe Leu Lys Lys Phe Met Gly B Met Leu Phe Lys Phe Gly Lys His C Leu His Lys Lys Phe Phe Gly Met D Leu His Phe Lys Lys Phe Met Gly E Gly Met Phe Lys Lys Phe His Leu 57