Free Radical Protection – Mechanisms of Cellular Injury

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.