Question

Using the pKa values given in the table on the right, determine the charge of the side group of the following amino acids at the pH specified. Consider the side group only (not including the charges at the C–terminal or N– terminal).

2. Using the pka values given in the table on the right, determine the charge of the side group of the following amino acids at the pH specified. Consider the side group only (not including the charges at the C-terminal or N- terminal). I filled first two rows for example. 1 point per row -no partial points. lonizable residue Amino Acid pka Charge of its side group at ... pH 3 +1 pH 10 3.9 N-terminal 4.1 6 C-terminal 0 asp glu his cys tyr lys arg C-term N-term 8.4 10.5 Tyrosine Cysteine 10.5 12.5 3.5 9.0 Lysine Aspartate Alanine

Answer 1

Charge on side groups of given amino acids:

At pH 3 :

• Tyrosine (-OH side group ): 0
• Cysteine (-SH ) : 0
• Lysine (NH3⁺) : +1
• Aspartate (-COOH) : 0
• Alanine (-CH₃) : 0

At pH 10 :

• Tyrosine : ~0 [- 0.2 ]
• Cysteine : -1
• Lysine : 0
• Aspartate (-COO^- ): -1
• Alanine : 0