Free Radical Protection – Mechanisms of Cellular Injury

by Richard Mitchell, MD

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    00:02 How do we protect ourselves against us? Well, fortunately, if free radicals don't encounter something, they do spontaneously decay.

    00:09 So those the electron gets paired and it will no longer be a free radical and quite so reactive.

    00:16 We have a number of enzymes, superoxide dismutase (SODs) that will turn superoxide free radical with a couple protons in the hydrogen peroxide and oxygen and we can further breakdown that hydrogen peroxide in just a second.

    00:30 So we have ways to degrade it.

    00:32 And we have high levels of these enzymes, where we expect high levels of free radicals to be generated.

    00:40 We have circulating and then in cells, particularly.

    00:44 A glutathione peroxidase system, and glutathione is a tripeptide.

    00:48 It's gamma-glutamyl cysteine glycine, which has a free self hydro-group, when it encounters oxygen free radicals that scavenges it and by making a disulfide bond and then the glutathione peroxidase turns that disulfide linked glutathione back into the native glutathione and we're good to go.

    01:09 So we have another mechanism and this is a normal tripeptide and a normal enzyme that exists exclusively to clear free radicals.

    01:19 Catalases, I mentioned we have a way to get rid of hydrogen peroxide, and we could break that down into water and oxygen.

    01:26 So we have multiple different mechanisms by which we can protect ourselves against free radicals.

    01:31 And we've also talked already about free radical scavengers such as Vitamin E.

    01:35 And it turns out that there are other proteins that we have circulating such a ceruloplasmin and others, whose job it is to wander around, find a free radical, scavenge it and inactivate it.

    01:47 Finally, let's talk about mitochondrial damage.

    01:52 And this is also an important mechanism by which we can get biochemical injury.

    About the Lecture

    The lecture Free Radical Protection – Mechanisms of Cellular Injury by Richard Mitchell, MD is from the course Cellular Injury.

    Included Quiz Questions

    1. Glutathione peroxidase
    2. NADPH oxidase
    3. Cytochrome C oxidase
    4. Xanthine oxidase
    5. Nitric oxide synthase

    Author of lecture Free Radical Protection – Mechanisms of Cellular Injury

     Richard Mitchell, MD

    Richard Mitchell, MD

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