MBMB 451b

Copyright 2000, E.C. Niederhoffer

Bonus Problem - Enzyme Kinetics

Initial studies of an esterase using a racemic mixture as substrate revealed that the L enantiomer was the true substrate, as it was completely converted into product, whereas the D enantiomer could be recovered unchanged at the end of the reaction. On the basis of this result the kinetics of the reaction were analyzed assuming that the D enantiomer had no effect on the enzyme, and a Michaelis constant for the L enantiomer was estimated to be 2 mM. Subsequent work made it clear that it would have been more reasonable to assume that the D enantiomer was a competitive inhibitor with KI equal to the Km value of the L enantiomer. How should the original Km estimate be revised to take account of this information?

For full credit, you must show your work (how you obtained your answer).

click here for the solution (pdf file)


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