Acid-Base Properties of Amino Acids Practice Problems

Draw the prevalent form of asparagine present in a solution of pH 6.

Determine whether valine (pI = 6.02) or cysteine (pI = 5.15) has a more negative charge at pH 7.0.

Explain why glutamic acid (pI = 3.08) elutes before threonine (pI = 5.60)  when their solution having pH 5 is passed through a cation-exchange column.

Explain why cysteine (pI = 5.15) elutes before isoleucine (pI = 5.60) when their solution having pH 5 is passed through a cation-exchange column.

Draw the predominant form of serine present in a solution of pH = 7.0. 

Draw the predominant form of serine present in a solution of pH = 12.0. 

Show the location and the type of charge on the tripeptide Gly-Ala-Ser at pH 6.0.

Show the location and the type of charge on the tripeptide Gly-Ala-Ser at pH 11.0.

Isoleucine has pK_a values of 2.36 and 9.68. Between what pH does isoleucine predominantly exist as a zwitterion?

Amino acid valine has pK_a values of 2.32 and 9.62. Determine the pH at which valine would exist in the following form.

Determine whether alanine (pI = 6.11) or serine (pI = 5.70) has a higher percentage of negative charge at pH 7.0.

Draw the predominant form of valine present in a solution with a pH of 6.

Draw the predominant forms of phenylalanine, tryptophan, and tyrosine present as a mixture at pH 7.

Draw the predominant form of threonine present in a solution with a pH of 12.

Show how electrophoresis can separate glutamic acid (PI 3.2), lysine (PI 9.7), and glycine (PI 6.0) from a solution having pH 6.