That never really goes away
Two free radicals will sometimes cancel each other out
frequently...usually... cancel each other out
This comes from the 'unpaired electron' language So,,,"a free radical is an unpaired electron"
Well, if you have two unpaired electrons, then they will cancel each other out.
free radicals are not very common
So, how do antioxidants fit into this? an antioxidant is a free radical donor
so, This is an example of an antioxidant. Kind of a representation
This could be vitamin C or vitamin A one of the many vitamin E's
There is a very very large number of antioxidants and they take on a lot of characteristics
and behave in a lot different ways. but the general pattern is that
the antioxidant gives up a free radical
so an example would be (if we look at this) the free radical would be a hydrogen particle
so the hydrogen particle comes over and combines onto the damaged aliphatic free radical
so this would be a carbon with seven electrons in its outer energy level
So it is unstable, very unstable.
The free radical donated by the antioxidant plugs the scar in the damaged cellular material
But, ...free radicals never really go away so if two free radicals can cancel each other out,
if the antioxidant is going to give up a free radical, it has to become a free radical itself
so the instability that was in the cellular material
that instability is now part of the antioxidant
So there is logical error here. so that the cell consumes antioxidants?
The glutathione system is designed to recharge the whole system
the whole antioxidant system is recharged with the glutathione system
so glutathione
glutathione is an antioxidant, like other antioxidants
glutathione consists of a glycine amino acid, glutamate amino acid and a cysteine amino acid.
recall that cysteine is one of the amino acids that has a sulfur group.
so we have the glycine, the glutamate and the cysteine is the one in the middle.
the sulfur group is the one we are interested in it is the sulfur group that donates the free radical
And it is the sulfur group that takes on the instability.... Sulfur is a big atom
and the instability in the sulfur group does not cause any problems
So...Glutathione
The sulfur group of the glutathione donates a free radical
and, in the process, becomes a free radical itself just like any other antioxidant
in many ways glutathione is a typical antioxidant
But glutathione has a trick I want to show it to you right here
two glutathiones, after they have become oxidized two glutathione can come together and
form, what they call a disulfide bond it is a very common bond in protein structure.
So this is one glutathione on this side another glutathione on this side
so this is the big tripeptide here and the big tripeptide here....
combine together with a disulfide bond
and then there is an enzyme, called glutathione reductase
(let me just write it out) glutathione reductase
which breaks this apart back into
the original
reduced, active form of glutathione so that the glutathione acts as an antioxidant, but
the glutathione has a recharge system. The glutathione turns into a dimer, between two of them
and then there is an enzyme that is specifically for this
This is an uphill (NaDH) energy reaction and it takes an NaDH to push it up
so it requires energy to make this reaction happen , like many reactions in biochemistry.
And the result of this is that the glutathione can be re...reduced back to its active form
The significance of all this is that glutathione is the big regeneration system
for all antioxidants...all antioxidants go to the glutathione system.
the glutathione brings them back to life
glutathione is the ultimate wastebasket it is the end wastebasket for free radicals
The glutathione antioxidant system is found in vertebrates, invertebrates
it is found in plants.
It is found in very nearly every type of bacteria
The antioxidant system,
this is like the grandmother
antioxidant system of them all