Unique features and function of all 20 major amino acids

A polypeptide has a high pI value. Suggest which aminoacids might comprise it

Instruction for the said activity: Write the structure of each of the following peptide at pH7 and identify how many peptide bond in each number. d. Alanyl-phenylalanine- aspartate- cysteine e. Threonyl- Isoleucyl-methionyl- leucine f. Lysyl-alanine -Phenylalanyl-tyrosyl- serine

Ionization State of Histidine.Each ionizable group of an amino acid can exist in one of two states, charged or neutral. The electric charge on the functional group is determined by the relationship between its pKa and the pH of the solution. This relationship is described by the Henderson-Hasselbalch equation. 1.Histidine has three ionizable functional groups. Write the equilibrium equations for its three ion-izationsand assign the proper pKa for each ionization. Draw the structure of histidine in each ionization state.What is the net charge on the histidine molecule in each ionization state? 2.Which structure drawn in (1) corresponds to theionization state of histidine at pH 1, 4, 8, and12?Note that the ionization state can be approximated by treating each ionizable group independently. 3.What is the net charge of histidine at pH 1, 4, 8, and 12? For each pH, will histidine migrate to-ward the anode (+) or cathode (-) when placed in an electric field?