Exam2 Spring 2008 KEY - Please answer all of the following...

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Please answer all of the following. Physical constants can be found on the back page. Good Luck! I hope the exam does not prove to be an April Fool’s joke. 1) A spacecraft has returned from Europa, a moon of Jupiter, where it has landed, drilled through the ice covering and recovered biological samples from the subsurface ocean. (A plausible scenario as of current knowledge and NASA planning; I’ll believe it when I see it.) From a small, sluglike creature you isolate an enzyme ( Glycol dehydratase ) which converts ethylene glycol to ethanol – i.e. antifreeze to vodka. HOCH 2 CH 2 OH + 2H + + 2e - CH 3 CH 2 OH + H 2 O The commercial possibilities are obvious. The slug’s body tissues also contain an inhibitor of the enzyme. You measure the velocity of the enzyme-catalyzed reaction at several substrate concentrations with and without the inhibitor. The enzyme concentration used for the experiment was 1 nM . a) On the graph paper provided, make a Lineweaver-Burke plot (3 pts) of the enzyme activity data with and without the inhibitor. What is Km for the uninhibited enzyme? _20 uM (5 pts) What is kcat for the uninhibited enzyme? _16.7 sec - 1___ (5 pts) b) Is the viral enzyme a very efficient catalyst? Why or why not and how can you tell? (I am more interested in the latter part than in a “yes” or “no”!) (5 pts) kcat/Km is a measure of efficiency, being a pseudo-first order rate constant for the catalyzed reaction. kcat/Km = 16.7/20*10
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This note was uploaded on 11/03/2010 for the course CH 369K taught by Professor Techniquesofresearch during the Spring '08 term at University of Texas at Austin.

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Exam2 Spring 2008 KEY - Please answer all of the following...

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