practice_final_exam

practice_final_exam - _ Name CHM 3218 Spring 2008 Practice...

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__________________________________ Name 1 CHM 3218 Spring 2008 Practice Final Examination University of Florida Honor Code Statement: "On my honor, I have neither given nor received unauthorized aid in doing this assignment." __________________________________ Student signature Instructions : You would have two hours to complete this exam. All books, notes and other aids would be prohibited, but calculators and molecular models would be allowed. Be sure to budget your time and answer questions briefly but completely. To receive partial credit for incorrect answers, be sure to show your work, particularly in problems involving calculations. Write your name on each page. 1. Isoleucine is catabolized by the multi-step pathway shown below. While we have not discussed these reactions in detail during class, they are very similar to ones we have covered. ( Total 35 points ). H 3 N CO 2 CH 3 CH 3 isoleucine O CO 2 CO 2 Glu O CO 2 3 CH 3 1 CoASH NAD + CO 2 NADH O SCoA 3 3 2 FAD O SCoA 3 CH 3 3 O SCoA 3 3 4 HO O SCoA CH 3 CH 3 5 O CoASH 3 SCoA O + SCoA 3 O acetyl-CoA propionyl-CoA Lipoamide a. Where a box appears above an arrow, predict the cofactor most likely to participate in the enzymatic reaction, if any. For the second reaction, indicate the additional cofactor not already shown. If no cofactor is predicted to be involved, write “None” in the box. Note that the names and structures of all cofactors discussed during lectures can be found on the final page of this exam. ( 3 points each ). b. Does the first reaction (isoleucine + α -ketoglutarate glutamate + 1 ) strongly favor reactants, strongly favor products or strongly favor neither? Briefly explain your answer. ( 3 points ).
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__________________________________ Name 2 c. Draw L-glutamate in Fischer projection form in the ionic form that would predominate at pH 8.0. ( 3 points ). d. What is the concentration of the form of L-glutamate with no net charge in 50.0 mL of solution with a total glutamate concentration of 25.0 mM at pH 2.50? A table of amino acid p K a values can be found near the end of the exam. ( 6 points ).
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__________________________________ Name 3 e. Use curved arrows to show a mechanism for the enzyme-catalyzed conversion of 1 + NAD + + CoASH 2 + CO 2 + NADH. Use the cofactor you indicated in part a. You may use acid-base catalysis as necessary. You do not need to show the latter part of the mechanism, which is concerned with converting reduced lipoamide back to the oxidized form. ( 8 points ).
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__________________________________ Name 4 2. Serine hydroxymethyltransferase catalyzes the reaction shown below. ( Total 14 points ).
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practice_final_exam - _ Name CHM 3218 Spring 2008 Practice...

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