Gly-Gln-Ser-Lys-Met-Thr-Asp-Asn-Tyr What is the net charge of this peptide at pH 7.0?
A) +2
B) +1
C) 0
D) -1
E) -2

Question

Quizplus · Accepted Answer

At pH 7.0, the carboxyl group of Asp and the amino group of Lys are both protonated, while the amino group of the N-terminus and the carboxyl group of the C-terminus are both deprotonated. The net charge of the peptide would be 0, since the positively charged amino acid side chains (Lys and Arg) are balanced by the negatively charged side chains (Asp and Glu) and the peptide termini are neutral.

Gly-Gln-Ser-Lys-Met-Thr-Asp-Asn-Tyr What Is the Net Charge of This Peptide at PH