Chemistry

  TWO PROBLEMS (30%) 1) You are given EIGHT molecules as follows: i. Pro-Gln-Gly-Met-Asn-Met-Phe-Pro ii. Glu-Asp-Gly iii. Ala-Leu-Lys-Gln-Asn iv. ATGC v. Gln-His-Arg-Gly vi. Phe-Trp-Gly-Leu-Glu-Asn-Cys vii. Val-Arg-Ala-Asp-Asn-Met-Glu-Ile viii. (n = 30) 1. Please predict the charges of the following EIGHT molecules as shown above under i) pH 1, ii) pH 7 and iii) pH 13. 2. You carried two-dimensional electrophoresis (first dimensional is done by isoelectric focusing, the 2nd dimension is done by SDS- PAGE) with the EIGHT molecules as mentioned above, please predict results at the end of two-dimensional electrophoresis. Please explain your predicted results based on the properties of the molecules. 3. Please draw the structure of Ala-Leu-Lys-Gln-IIe, by keeping the nature of peptide bond in mind. [60 points] 2) The question concerns the buffering effect of acid/base system. 1. i) What is the pH of a solution of that contains 0.15 M Na+H2PO4- and 0.65 M (Na+)2HPO42-? 2. ii) What would the concentration of Na+H2PO4- be at pH 6 if 0.15M (Na+)2HPO42- was adjusted to that pH. 3. iii) What would be the concentration of Na+H2PO4- be at pH 3 if the solution in ii was adjusted to that pH. Please provide the rationale behind this calculation. [40 points]