A. The polypeptide: DFEVDERGYQTICMKNYS is subjected to trypsin where it cleaves at lysine and arginine residue. What are the peptide fragments after digestion and what fragment would flow most slowly in a gel filtration column?
B. What is the overall net charge of the polypeptide: Ala-his-trp-asp-leu-lys at pH 7 and pH 9. Consider only predominant charges at these ph value and show work
Table. Typical pKa values of ionizable groups in proteins Ionizable functional group pKa erminal a-carboxyl group Aspartic Acid (R-carboxyl) Glutamic Acid (R-carboxyl) Histidine (R-imidazole Terminal a-amino grou Cysteine (R-SH) Tyrosine (R-OH) Lysine (R-NH2) Arginine (R- guanidine) 3.1 4.1 4.1 6.0 8.0 8.3 10.9 10.8 12.5