3K - Net ID _KEY A_ BIOBM3310 QUIZ 3a 9/23/09 1. (8 pts)...

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Net ID __KEY A ____ BIOBM3310 QUIZ 3a 9/23/09 by which prolyl isomerase lowers the barrier for peptide cis/trans isomerization, given that: (RATE cat / RATE uncat ) = (exp - G o ± /RT ) cat / (exp - G uncat R = 0.00832kJ/mol x K and T = 300K G o RATE cat /RATE uncat = 2000. 2000 = e - ( G o /RT) ln(2000) = - ( G o /RT) 7.6 = - ( G o )/2.5kJ/mol ( G o ) = 19 kJ/mol 2. (8 pts) Use the diagram to the right to describe the protein ribonuclease (RNase). Three different conditions occur. Draw directly on the diagram appropriate plots for RNase. Label plots as a, b, and c. "N" is the location of native structure on the structural coordinates axis. a. Physiological conditions b . In 8M urea plus HO-CH 2 CH 2 SH c . After condition b, (above), followed by extensive dialysis, then air oxidation. Full enzymatic activity is recovered by this procedure. d. Procedure (c) takes 10 hours. But in a cell, folding takes 2 minutes. Check the one reason for this time difference: In a cell, an enzyme speeds disulfide interchange In a cell, proteins are "crowded", speeding the folding In (c), proteins are "crowded", slowing the folding In a cell, enzymes speed up the Φ,Ψ rotations STRUCTURAL COORDINATES 3. (5 pts) Consider G = H - T S for the “reaction” PROTEIN unfolded PROTEIN folded Circle T if true, F if false: T/F The entropy of the protein , not considering the water, is much lower in the folded state. T/F The entropy of the water is much lower when the protein has folded. T/F Of all the interactions driving a water-soluble protein to fold, the hydrophobic interaction is the most important. T/F The hydrophobic interaction becomes larger and larger the higher the temperature, in the range 0 - 40 o C. T/F All cells need "chaperone proteins" to prevent aggregation of large, newly synthesized proteins. 4. (5 pts) Consider a schematic diagram of the native (folded) structure of a multi-fold protein : Circle T if true, F if false, for each of the following statements about this diagram T/F Six polypeptides associating in IV (quaternary) structure are indicated T/F Shown is one single polypeptide, with a total of six folds T/F
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This note was uploaded on 09/19/2010 for the course BIOBM 3310 taught by Professor Feigenson,gw during the Fall '07 term at Cornell University (Engineering School).

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3K - Net ID _KEY A_ BIOBM3310 QUIZ 3a 9/23/09 1. (8 pts)...

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