Finding net charge on a peptide?
 

Consider the net charge on the peptide AAAADEHKRAAA dissolved in an aqueous solution. Suppose the pH is raised from 2 to 8.5. Ignoring the charges that may exist on the N- and C-termini, what is the correct charge on the peptide?

a. from +2 to +5
b. from +3 to +5
c. from +3 to 0.
d. from 0 to +2

Thanks so much!

Re: Finding net charge on a peptide?
 

C) +3 to 0

At pH 2 Side chain Asp (D) and Glu (E) having 0Charge while His(H), Lys(K),Arg (R) having +1 Charge each so total +2 charge .

Net charge at pH 2 is +3 (Ignoring N and C termini amino acid)

At pH 8.5 Side chain Asp (D) and Glu (E) having -1 Charge each so total -2 Charge while His(H) having 0 charge , while Lys(K),Arg (R) having +1 Charge each so total +2 charge

Net charge at pH 8.5 is 0 (+2 - 2) (Ignoring N and C termini amino acid)