Influence of selenium and/or magnesium on alleviation alcohol induced oxidative stress in rats, normalization function of liver and changes in serum lipid parameters.

The aim of this study was to evaluate the attenuating effect of given selenium and/or magnesium on ethanol-induced oxidative stress, disturbances of liver function and cholesterol metabolism. Forty male rats were divided into five groups: C - control, Et - intoxicated with alcohol (15% solution in drinking water), Et + Mg, Et + Se, Et + Mg + Se - intoxicated with alcohol and supplemented with selenium (0.4 mg Se/l water), magnesium (100 mg Mg/l water) and combination of Se and Mg, respectively. The experiment was carried out over the 3 months. The results show that the chronic ingestion of alcohol induces lipid peroxidation and histopathological changes in liver. Supplementation with magnesium only partially alleviates oxidative stress and damages in this tissue. The both selenium alone and combination of magnesium and selenium significantly elevated total antioxidant status (TAS) in serum, activity of glutathione peroxidase and ratio of reduced glutathione to oxidized glutathione (GSH/GSSG) in liver and retarded oxidative stress and histopathological changes in this tissue. Chronic administration of ethanol (alone and with magnesium) resulted in significant decrease in the serum total cholesterol and retardation in the body weight gain in comparison with the control group. In the groups supplemented with selenium and selenium and magnesium simultaneously, concentration of total cholesterol in serum and body gains was similar to the control group. Supplementation of Se or selenium and magnesium simultaneously significantly enhances antioxidant defence and is more effective against alcohol-induced oxidative stress, disturbance of liver function and cholesterol metabolism than the separate use of magnesium.

[Structure and biogenesis of cytochrome b6f complex]. / Budowa i biogeneza kompleksu cytochromów b6f.

Both photosynthetic cytochrome b6f complex, and respiratory cytochrome bc1 belong to the family of cytochrome bc complexes. Both protein supercomplexes participate in the transport of electrons, proton translocation through the biological membrane, and they catalyze chinon oxidation as well. The function, composition, spatial organization and biosynthesis of cytochrome b6f complex has been being the subject of research for years. The obtained crystal structures revealed the presence of the third haem in the cytochrome b6, whereas mutagenic experiments indicated the participation of the additional protein factor (TCA) engaged in the regulation of b6f cytochrome complex synthesis through the interaction between TCA and 5'UTR of the PETA transcript. The following compendium is the collection of the current data and knowledge with reference to the structure and biogenesis of the above mentioned protein complex.

Integration of the thylakoid membrane protein cytochrome b6 in the cytoplasmic membrane of Escherichia coli.

An overexpression system for spinach apocytochrome b(6) as a fusion protein to a maltose-binding protein in Escherichia coli was established using the expression vector pMalp2. The fusion of the cytochrome b(6) to the periplasmic maltose-binding protein directs the cytochrome on the Sec-dependent pathway. The cytochrome b(6) has a native structure in the bacterial cytoplasmic membrane with both NH(2) and COOH termini on the same, periplasmic side of the membrane but has the opposite orientation compared to that in thylakoid. Our data also show that in the E. coli cytoplasmic membrane, apocytochrome b(6) and exogenic hemes added into a culture media spontaneously form a complex with similar spectroscopic properties to native cytochrome b(6). Reconstituted membrane-bound cytochrome b(6) contain two b hemes (alpha band, 563 nm; average E(m,7) = -61 +/- 0.84 and -171 +/- 1.27 mV).