Irreversible Enzyme Inhibition: Suicide – Enzyme Inhibitors

by Kevin Ahern, PhD

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    00:01 The three mechanisms of enzyme inhibition that I have talked about so far competitive inhibition, non-competitive inhibition and uncompetitive inhibition are fundamentally different from the one I am getting ready to talk about here.

    00:12 In each of those cases, the binding of the inhibitor to the enzyme was a reversible process.

    00:17 The inhibitor could go on. But the inhibitor could also come off and these are very common inhibition mechanisms.

    00:23 The mechanism I am getting ready to describe here called suicide inhibition is different completely from them.

    00:27 In suicide inhibition, what happens is the inhibitor that binds with the enzyme does so irreversibly.

    00:35 And it does it irreversibly; because, the inhibitor makes a covalent bond with the enzyme at the active site.

    00:41 The enzyme can't shake and the inhibitor loose and as a consequence the enzyme is completely put out of action.

    00:48 Now example of a reaction like this occurring is that of the action of penicillin which we used to kill bacteria.

    00:55 Penicillin works; because, what it does is it inhibits the bacterium's ability to make cell walls.

    01:01 Well cell walls are pretty important for cells; because, without a wall you don't have a cell.

    01:05 The way that this works, is penicillin mimics the normal substrate that the enzyme that makes the cell walls uses, that's the pentaglycine chain.

    01:13 Because penicillin resembles it and the enzyme binds to it, like it would bind to the normal substrate, but penicillin makes the covalent bond.

    01:20 So when suicide inhibition, the enzyme is completely destroyed and never gets a chance to come back into its thing.

    01:25 Well in this series of lectures what I have talked about are different types of inhibition. A reversible set of inhibitions that included: the competitive, non-competitive and uncompetitive.

    01:36 And now suicide inhibition that is an irreversible enzyme inhibition.

    01:40 Our understanding of enzyme inhibition is important for anyone interested in understanding the mechanism by which drugs work or designing drugs themselves.

    About the Lecture

    The lecture Irreversible Enzyme Inhibition: Suicide – Enzyme Inhibitors by Kevin Ahern, PhD is from the course Enzymes and Enzyme Kinetics.

    Included Quiz Questions

    1. Inhibitors resemble the natural substrate
    2. Inhibitors bind non-covalently to a site away from the active site
    3. Vmax is increased
    4. Km is decreased

    Author of lecture Irreversible Enzyme Inhibition: Suicide – Enzyme Inhibitors

     Kevin Ahern, PhD

    Kevin Ahern, PhD

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    Great enzyme lectures
    By VICTOR P. on 21. October 2017 for Irreversible Enzyme Inhibition: Suicide – Enzyme Inhibitors

    As a medical student I found this series of lectures on enzymes extremely clarifying. Dr Ahern is a great lecturer. Thank you so much.