Unformatted text preview: to possess a high % content of β-sheet ________ 9 Question #9 (8 points)
The diagram below is a 37 amino acid alpha-helical blood protein synthesized by polar fish known as the winter
flounder. The protein is a biological “antifreeze”. It inhibits ice crystal formation and helps to keep the fish’s
serum liquid below 0oC. (a) Estimate ∆HH-bond /mol for the folding of the protein in water. Consider only H-bonds involving the peptide
linkages of the polypeptide backbone. That is, ignore anything to do with R-groups (amino acid side chains)
and the N and C termini.
Before doing the calculation note the following assumptions! ASSUME
(1) the energy (at 25oC/1 atm) required to break a H-bond between C=O and H-N in an α-helix = 15 kJ/mol.
(2) the energy (at 25oC/1 atm) required to break a H-bond involving H2O = 12 kJ/mol.
(3) that all H-bond acceptor atoms accept only one H-bond.
(4) the 4 “unsatisfied” backbone C=O and N-H groups maintain their H-bonds with water in the folded state.
This is IMPORTANT! For FULL credit, you must CLEARLY indicate your reasoning. If your
answer is illegible or if there is ANY doubt about your reasoning, “0” points will be awarded. A
verbal clarification of your method following exam grading will NOT be considered. You may want
to write out your ans...
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This test prep was uploaded on 04/01/2014 for the course BIOL 201 taught by Professor Chowrira during the Winter '13 term at UBC.
- Winter '13