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Homework 3
Chem 452-.Due Friday, November 3 (10 pts.).
Enzyme Kinetics and Drug Design
NAME
Sphingosine-1-phosphate has recently been discovered to be important for cell growth. The synthesis of SPP from sphingosine and ATP is catalyzed by the enzyme sphingosine kinase. An understanding of the kinetics of the sphingosine kinase reaction may be important in the development of anti-neoplastic drugs. The velocity of the sphingosine kinase reaction was measured in the presence and absence of 5 µM threo-sphingosine, a stereoisomer of sphingosine. The results are shown below: SHOW YOUR WORK AND INCLUDE A GRAPH.
Use a Linewever-Burk plot or do a direct fit if you know how to do that, and answer the following.
a) What are Km and Vmax in the presence and absence of inhibitor?
b) What kind of inhibitor is threo-sphngosine (remember this is actual data and so it will not be perfect; use some judgement)? What is KI?
c) Inhibitor A has an extra methyl goup which increases it's KI value over threo-sphingosine. Inhibitor B has an added hydroxyethyl group which lowers it's value of KI. Which inhibitor is likely to be the best drug and explain why.