Protein SgpR of Pseudomonas putida strain AK5 is a LysR-type regulator of salicylate degradation through gentisate.

Pseudomonas putida strain AK5 was the first characterized natural strain containing the 'classical' nah1 operon and nahR gene along with genes whose products are responsible for the less explored pathway of salicylate degradation through gentisate (the sgp operon). The sgp operon was found to be preceded by the divergently directed sgpR gene. The amino acid sequence of the sgpR product qualifies it as a LysR-type transcriptional regulator (LTTR) and suggests its potential function as an sgp operon transcriptional regulator.

Flavonoids determine the rate of fibrillogenesis and structure of collagen type I fibrils in vitro.

Collagen fibrils are produced from collagen monomers not only in vivo, but also in vitro. The ability to have an influence on the structure and properties of fibrils may find medical application and can be useful for controlling the formation of collagen gels and sheets in tissue engineering. Here we investigated the influence of flavonoids, distinguished by the number of hydroxyl groups in the B-ring, on the formation of collagen fibrils.

Integration of Quercetin-Iron Complexes into Phosphatidylcholine or Phosphatidylethanolamine Liposomes.

It is well known that flavonoids can chelate transition metals. Flavonoid-metal complexes exhibit a high antioxidative and therapeutic potential. However, the complexes are frequently hydrophobic ones and low soluble in water, which restricts their medical applications.

Flavonoid-membrane interactions: involvement of flavonoid-metal complexes in raft signaling.

Flavonoids are polyphenolic compounds produced by plants and delivered to the human body through food. Although the epidemiological analyses of large human populations did not reveal a simple correlation between flavonoid consumption and health, laboratory investigations and clinical trials clearly demonstrate the effectiveness of flavonoids in the prevention of cardiovascular, carcinogenic, neurodegenerative and immune diseases, as well as other diseases. At present, the abilities of flavonoids in the regulation of cell metabolism, gene expression, and protection against oxidative stress are well-known, although certain biophysical aspects of their functioning are not yet clear.

[Study of membranotropic and antioxidant activity of flavonoids and their complexes with ferric iron].

We studied the interaction with liposomes and the antioxidant activity of flavonoid (quercetin, catechin, taxifolin) complexes with iron (III). It was found that the lipophilicity of complexes depends on an iron:flavonoid ratio and grows at a ratio of 1 to 1, while complexes in a 2:1 ratio were the most effective to slow down the lipid peroxidation and restore radical 2,2-diphenyl-1-pic: rylhydrazyl. Thus, the stoichiometry of complexes formed in aqueous solution, may differ from the stoichiometry of complexes that most effectively protect membranes from.

Lipophilicity of flavonoid complexes with iron(II) and their interaction with liposomes.

We studied complex formation of flavonoids quercetin and taxifolin with iron(II) and the complex influence on phase transitions of phospholipid bilayer. UV-Vis spectroscopy revealed that the stoichiometry of flavonoid/iron complexes was equal to 3:2 and 2:1. Molecular modeling and experimental measurements demonstrated the increase of flavonoids lipophilicity after the complex formation.

Calcium-dependent aggregation and fusion of phosphatidylcholine liposomes induced by complexes of flavonoids with divalent iron.

It was found that complexes of the flavonoids quercetin, taxifolin, catechin and morin with divalent iron initiated an increase in light scattering in a suspension of unilamellar 100nm liposomes. The concentration of divalent iron in the suspension was 10μM. Liposomes were prepared from 1-palmitoyl-2-oleoylglycero-3-phoshpatidylcholine.

Rafts making and rafts braking: how plant flavonoids may control membrane heterogeneity.

Plant flavonoids are not only known as powerful antioxidants, but also as cell metabolism regulators. It has been postulated that they are able to control cell signal pathways by targeting receptors on the cell surface or by intercalating the lipid bilayer of membranes. Some flavonoids can increase lipid viscosity and decrease the cooperativity of hydrocarbon chain melting, while others can considerably decrease the lipid melting temperature, thus providing additional freedom for lipid diffusion.

[Structural changes in lipid membranes and collagen irradiated with UV light and the protective effect of plant extracts].

The results of experimental studies on the effect of UV irradiation on collagen, artificial lipid membranes, and rat skin, as well as the protective effect of plant extracts from UV radiation are presented. The irradiation of collagen and lipid membranes with solar and artificial UV light leads to structural changes in these objects. In particular, collagen molecules denature and transfer into a new conformational state.

4-Hydroxyphenethyl alcohol--a new cytokinin-like substance from the phototrophic purple bacterium Rhodospirillum rubrum 1R.

Three compounds with cytokinin activity have been isolated from the medium of Rhodospirillum rubrum grown photosynthetically. Two N-6 aminopurine cytokinins revealed in the medium were identical with those obtained from R. rubrum cells previously.

[Effect of quercetin on electron transfer in photosystems I and II of pea chloroplasts].

The effect of such flavonoid as quercetin and its oxidized from on electron transfer was studied in subchloroplast preparations of the Photosystem II (PS(2) and Photosystem I (PS(1)). Quercetin and its oxidized form are shown to inhibit the electron transfer in the PS(2) acceptor and donor sites, respectively. They also function as an electron donor or and electron acceptor in PS(1)), respectively

[Effect of indoleacetic acid on the proton conductivity of biological membranes].

The effect of indolylacetic acid (IAA) on proton conductivity of tylacoid membranes of isolated pea chloroplasts at pH 5.5-8.0 and of artificial phospholipid membranes at pH 7.

[Inhibition of electron transport and photophosphorylation in chloroplasts by quercetin].

The influence of quercetin on electron transport and photophosphorylation of pea isolated chloroplasts with methylviologen and NADP+ has been studied. Quercetin inhibits ATP synthesis and phosphorylating electron transport but does not affect the basal electron transport in the presence of methylviologen. In view of these data and because of the increase of the proton uptake by chloroplasts in the presence of quercetin we consider it as an inhibitor of energy transfer.

Investigation of electron transport in the chloroplasts and their fragments by the ESR method. II. Light-induced interaction of water-soluble nitroxide radical with chloroplasts and chlorophyll containing protein-lipid micelles.

A light-induced reduction of the water-soluble nitroxide radical by chlorophyll in lipid and protein--lipid micelles was demonstrated. In contrast to model systems, in whole chloroplasts the NR is photoreduced by the electrons of the noncyclic electron transport chain. The initiation of cyclic electron transport in light particles, containing only photosystem I, does not lead to photoreduction of NR.