The amino acid proline has a pk1 of 1.99, pk2 of 10.60. the amino acid serine has pk1 of 2.21 and a of pk2 of 9.15. if these two amino acids bind together by peptide bond creating the peptide sequence pro-ser . what will be the overall charge of this peptide at the physiological ph of 7? a) overall charge will be neutral b) overall charge will be neutral on pro and negatively charged on the ser c) overall charge will be negative d) overall charge will be positive due to the presence of the peptide bond