Answer the following eight questions (a through h) based upon a tripeptide sequence of the following amino acids (one-letter codes are given):
S (serine) P (proline) K (lysine)
What is the overall charge on the tripeptide at physiological pH (pH 7.4)?
For each of the amino acids, is the side chain (R group) hydrophobic, polar but uncharged, positively charged, or negatively charged at physiological pH?
What is the overall charge of the tripeptide below pH 1.0?
What is the overall charge of the tripeptide at pH 12?
What type of intermolecular attractions could the side chains of the amino acids make with the solvent (water) at pH 7.4? (Note that these are attractions with water, not with other amino acids.)
If the tripeptide was dissolved in a buffer that is pH 8.5, what would be the net charge on the most abundant chemical species?