ProblemSet3 - Chemistry 114A 2007 Problem Set#3 1 Which tripeptide is most negatively charged at pH7.0 a Tyr-Lys-Met b Gly-Pro-Arg c Asp-Trp-Tyr d

Chemistry 114A, 2007 Problem Set #3 1. Which tripeptide is most negatively charged at pH7.0? a. Tyr-Lys-Met b. Gly-Pro-Arg c. Asp-Trp-Tyr d. Asp-Ala-Glu e. Leu-Val-Phe 2. The chemical structures of four amino acids are depicted above and they are labeled I, II, III, and IV. Use your knowledge of amino acid nomenclature, structure, and chemistry to answer the following questions. Answer with the Roman numeral unless otherwise instructed. A) What is the single letter code of amino acid I? B) Which of these does not carry a neutral charge at pH 7? C) Which amino acid is classified as aromatic? D) What is the three letter code of amino acid III? A) What is the isoelectric point (pI) of I? B) Which amino acid contains the indole side group? C) Which cannot form hydrogen bonds through its side group? D) Which has a polar uncharged side group? 3. The salting in of proteins can be explained by: A) salt counter-ions reduce electrostatic attraction between protein molecules B) proteins attracting primarily salt cations C)