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Unformatted text preview: Chem 237 DE S 08 Assignment #1 ANSWERS 1. For the following two peptides, draw the chemical structure of both peptides, indicating where the peptide bonds are. Also indicate the N- and C-termini. i. Pro-Arg-Trp-Gln ii. His-Thr-Asp-Cys ANSWER: 5 marks for each structure: 1 mark for each amino acid, 1 mark for C and N termini and 1 mark for the peptide bond. I have drawn the fully protonated peptide in both cases. N H 2 + H N N H H N COOH O O O HN H 2 N NH NH 2 + H 2 N O N-terminal C-terminal + H 3 N H N N H H N COOH O O O H 3 C COOH HS OH H + N HN N-terminal C-terminal The peptide bond is the amide bond that is found between the amino acids: H N O b. Draw a titration curve for both of these peptides. Be sure to label the axes properly, indicate the p K a values, the equivalence points and the buffering regions. For each curve, 1 mark for the correctly labeled axes, 1 mark for indicating the endpoints (equivalence point) 1 mark for indicating the pKas, and 1 mark each for the actual pKa values...
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This note was uploaded on 07/10/2010 for the course CHEM 237 taught by Professor Elisabethdaub during the Spring '10 term at Waterloo.
- Spring '10