__________________________________ Name 1 CHM 3218 / CHM 5305 Summer 2011 Practice Examination #2 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 molecular models and calculators would be allowed. Be sure to budget your time and answer questions briefly but completely. To receive partial credit for incorrect answers, show your work, particularly in problems involving calculations. Write your name on each page.1. Nucleoside phosphorylases are important enzymes that have been intensively studied for treating several diseases. This problem explores some of their chemistry. Note that throughout this problem, the “A nucleoside” means the nucleoside with the A base, not any nucleoside.(Total 38 points). a. Draw the complete structure of the A nucleoside. (4 points). b. Draw the complete structure of the open-chain form of D-ribose in Fischer projection form. (4 points).
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__________________________________ Name 2 c. Kinetic studies have shown that nucleoside phosphorylases follow a random mechanism for both substrate binding and product release. Use the Cleland notation to show this pattern for the reaction shown below. (4 points). d. Based on the kinetic mechanism in part c and your knowledge of carbohydrate mechanisms, use curved arrows to draw a mechanism for the enzyme-catalyzed conversion of the A nucleoside + Pito adenine and D-ribose-1-phosphate. You may use acid-base catalysis as needed. (8 points).