Polyunsaturated fatty acids (PUFA) undergo the LPO. Initiators of LPO are active forms of oxygen (AFO) (see the theme “The types of oxidation in section Bioenergetics”).

LPO includes the following reactions:

1) interaction of PUFA with active forms of oxygen (free radicals), giving radicals of PUFA

2) radicals of PUFA interact with molecular oxygen, yielding peroxide radical of PUFA

3) peroxide radical of PUFA interacts with hydrogen and this results in formation of hydroperoxide of PUFA

4) hydroperoxide of PUFA can be used by 2 pathways: a) it is cleft to saturated and unsaturated aldehydes which are further oxidized to malondialdehyde. Malondialdehyde is eliminated as end product of LPO through the kidneys. This pathway occurs without any enzymes. B) hydroperoxide of PUFA can be utilized with enzyme Glutathione peroxidase. During this reaction it is reduced to hydroxyacids, simultaneously glutathione is oxidized. Restoration of glutathione occurs under action of glutathione reductase.

Diene conjugates, hydroperoxides of lipids, malonic aldehyde and hydrocarbons are natural metabolites of cells because LPO occurs in normal conditions with a small velocity which is regulated by antioxidant system (AOS).

LPO is a main pathway of PUFA degradation. Metabolites of LPO are necessary for synthesis of some hormones (for example thyroid hormones), proteins, prostanoids, function of phagocytes, regulation of permeability and composition of membrane, velocity of proliferation and secretory function of cells.

However it is need to consider that increase of LPO and concentration of LPO metabolites cause the lesion of cells and its death, for example, metabolites of LPO destroy DNA and RNA that results in mutations. LPO products cause the denaturation of Proteins, disconnect Biologic oxidation (BO) and oxidative phosphorylation (OP), destroy the structure of membranes

The pathways of usage of acetylCoA. the biosynthesis of free fatty acids, ketone bodies and cholesterol. the cholesterol metabolism. final products of lipids metabolism

<== попередня сторінка	\|	наступна сторінка ==>
Beta-oxidation of FFA and its energetic value	\|	The biosynthesis of FFA

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