Acid-Base Properties of Amino Acids Practice Problems
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.
Isoleucine has pKa values of 2.36 and 9.68. Between what pH does isoleucine predominantly exist as a zwitterion?
Amino acid valine has pKa 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 forms of phenylalanine, tryptophan, and tyrosine present as a mixture at pH 7.