By analyzing the charges of all ionizable groups in this peptide (shown in the attached table), we can conclude that the net charge of the molecule at pH 3 will be +3, at pH 8 it will be +1, and at pH 11 it will be 0.
To answer this question, we must look at the pKa values of all the groups that can be ionized in this peptide.
Glu is glutamic acid, and because it is located on the N-terminus of this peptide, we need to consider its amino group (pKa = 9.67) and its side-chain carboxylic group (pKa = 4.25). For histidine (His) the only relevant group is the one in its side-chain (pKa = 6.00). Tryptophan (Trp), serine (Ser), one of the glycines (Gly), leucine (Leu), and proline (Pro) do not have side chains that can be ionized and their amino and carboxylic groups are engaged in the peptide bonds, so we do not have to consider them for this. However, we have to consider arginine's (Arg) side chain (pKa = 12.48) and C-terminus glycine's carboxylic group (pKa = 2.34).
Based on this, we can construct a table (attached below) that shows what charge (if any) the listed groups will bear at the given pH values, and sum them up to calculate the net charge.
You can learn more about peptides here:
brainly.com/question/14902522
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