Please draw the structure of the amino acid Histidine at each ionization state and please also give their net charges.

a. Suppose that you have the peptide Ala-Gly-Tyr-His-Leu and you treat it with FDNB and then 6M HCl. Draw the structures of all the products that you will have in solution (assume all reactions to go to completion).

You have a peptide that has the following amino acid sequence: GPMG Draw the structure of the polypeptide's most protonated form, and its charge. Then draw the structures of the increasingly deprotonated forms, along with their charges. Use the information from these structures to calculate the pl (isoelectric point) of the peptide using the pKa values provided in the table below. Write the pl as x.yz, for example, 7.62 or 3.09. Group Terminal a carboxyl group Aspartic acid Glutamic acid Histidine Terminal a-amino group Cysteine Lysine Tyrosine Arginine Acid EM 2-0" + H -N H H N-H H N-H T Base 1 1. تر H -5 H H O™ N-H Typical pK, 3.1 4.1 6.0 8.0 8.3 10.8 10.9 12.5

Identify the structure of the predominant form of the pentapeptide at pH = 12 if there is a pentapeptide Ile-Lys-Asp-Phe-Gly