Calculate the pI for arginine (the pK_a values—or the pK_a values for the conjugate acids of bases—are given).

Draw the following amino acids in all possible protonation states as you move from high pH to low pH.

b. His

Draw the electrophoretic separation of Ala, Lys, and Asp at pH 9.7.

Predict the predominant form and net charge of tyrosine (Y) at pH 10. What is the net charge? 

Determine the net charge of the dipeptide R-C at pH 4.3. (Hint:Peptide bonds do not count)

Glycine has pK_a values of 2.34 and 9.60. At what pH does glycine exist in the forms shown?

a.

Alanine has pK_a values of 2.34 and 9.69. Therefore, alanine exists predominately as a zwitterion in an aqueous solution with pH >____ and pH <____.

Identify the location and type of charge on the hexapeptide Lys-Ser-Asp-Cys-His-Tyr at each of the following pH values:

d. pH=12