29. Amino Acids

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

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

c. pH=7

Draw the form of aspartate that predominates at the following pH values:

d. pH=11.0

Draw the form of aspartate that predominates at the following pH values: c. pH=6.0

Draw the predominant form for glutamate in a solution with the following

pH: b. 3

Draw the predominant form for glutamate in a solution with the following pH:

a. 0

c. Which amino acid has the greatest amount of negative charge at pH = 6.20?

Draw the pH–activity profile for an enzyme that has one catalytic group at the active site:

a. the catalytic group is a general-acid catalyst with a pK_a = 5.6.

Draw the pH–activity profile for an enzyme that has one catalytic group at the active site:

b. the catalytic group is a general-base catalyst with a pKa = 7.2.