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    Picking the Best Inhibitor when Given Km, Kcat and Ki

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    Here are the following numbers I have calculated;
    We were given a substrate to plot againist velocity and 3 enzymes to plot as well. From the data:
    Enzyme A Ki= 2.575 | Kcat = 50 | Km= 3.33
    Enzyme B Ki = 10.33 | Kcat = 16.65 | Km = 33.3
    Enzyme C Ki= 1.00 | Kcat = 10 | Km = .2

    I'm having trouble understanding which is the best inhibitor because:
    A has the highest Kcat- best collision efficiency
    C has the lowest Km - the highest affinity for its substrate
    C has the lowest Ki- which means it binds the tightest.

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    Solution Preview


    The answer depends on what you want from your inhibitor as there is no clear best chemically.

    Km is the substrate concentration required for the enzyme to work at half its maximum rate. Purely competitive inhibition will increase Km but will not alter kcat (and hence the maximum rate). ...

    Solution Summary

    The solution offers guidance and things to consider to pick the best inhibitor out of three when given their respective Kcat, Km and Ki values. The velocity is plotted against the substrate.