Practice Final

2 glycine glycylglycine h2o keq 02 assume that the

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Unformatted text preview: H2O Keq’ = 0.2 Assume that the following concentrations of products and reactants are maintained at the following steady state levels during the reaction in the cell: [Glycine] = 5 mM [Glycylglycine] = 50 µM [H2O] = 55.5 M (b) If the hydrolysis of ATP to AMP and PPi is going to supply the energy to synthesize 1 mol of glycylglycine in (a) the value of Qcell’ value for the ATP hydrolysis cannot equal or exceed a certain value. Calculate this value. (5 points). ATP + H2O AMP + PPi + H+ ∆Go’ = -31.8 kJ/mol Page 6 (c) Provide an “arrow-pushing” mechanism for the real synthetase catalyzed reaction based on the mechanisms of other anabolic reactions. Note: the mechanisms presented in class did not show any enzyme active site residues nor did they keep track of protons (H+). You can use the following symbols for ATP also used in class: O O Adenosine O P O O OP - O O - O P O O - - O AMP O P OP O - O O - - Note: To indicate the mechanism use only 4 arrows. Do not include arrows for rearrangements indicating the changes in geometry around P (Step #1) or C ( Step #2) (2 x 4 points = 8 points). H NH3 + C H O C O - Glycine (d) In your mechanism, indicate which molecule is the “high energy intermediate”(2 points) Page 7 Question #3 (14 points) In the laboratory artifical electron donors can be used to donate electrons to the ETC components. One such artificial electron donor is “hexaammineruthenium” Reduced Form Oxidized Form Ru(NH3)6+2 Ru(NH3)6+3 (a) (2 points) The oxidized and reduced forms differ by _________ electron(s) and ___________ proton(s). (b) In laboratory experiments, the following oxygen consumption curve was obtained for intact mitochondria incubated in the presence of Ru(NH3)6+2, O2, ADP and Pi. Add Ru(NH3)6+2 Add rotenone [O2] Add antimyin A Add cyanide Time (i) (2 points) Which two components of the ETC could be accepting electrons from Ru(NH3)6+2? Component #1 ___________________ Component #2 ___________________ (ii) (2 points) What is the expected P:O ratio in each case? P:O if donating to Component #1 _________ P:O if donating to Component #2 __________ Page 8 (c) In the laboratory, Ru(NH3)6+3 can be used to carry electrons from reduced ascorbic acid to the ETC ulimately to O2 CH2OH CHOH O HO OH Ru(NH3)6 Ascorbic acid (Ox) O Ascorbic acid (Red) Ru(NH3)6 +2 - H 2O e +3 ETC O2 Reduced ascorbic acid (i) (4 points) The equation for the oxidation of ascorbic by oxygen is C 6 H 8 O 6 + 1 /2O 2 C6 H 6 O 6 + H2 O Keq’ = 4.4 x 1025 Assuming standard conditions for the oxidation of asc...
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