net charge on cysteine amino acid

Question

net charges on amio acid

Answer 1

The net charge on cysteine (amino acid), as well as any amino acid will depend on the pH of the solution.  For cysteine, the pKa for the carboxyl group is 1.7, that for the amino group is 10.8, and that for the SH group is 8.3.  So, depending on the pH, the carboxyl group will either be protonated (pH < 1.7) or not, and similarly for the -SH group (pH < 8.3), and the amino group which is be protonated at pH > 10.8