[Mechanism of hepatoprotective action of methionine and composition "Metovitan" against a background of antituberculosis drug administration to rats].

Oral administration of antituberculosis drugs to rats for 60 days in doses that are equivalent to clinical ones, causes changes in mRNA levels expression of liver cytochrome P-450 isoforms CYP3A2, CYP2C23, CYP2E1 and pro- and antioxidant state. Experimental composition "Metovitan" given with anti-TB drugs provided a correction of these abnormalities, that is evidenced by modulation of the level of CYP3A2, CYP2C23, CYP2E1 gene expression and antioxidant activity, inhibition of lipid peroxidation. "Metovitan" normalizes the enzymatic activity and content of total billirubin in the blood serum, shows high hepatoprotective properties, exceeding the efficiency of methionine.

[Oxidized derivatives of thiamine: formation, properties, biological role].

The data available in literature about formation, properties, possible biological role and practical application of the oxidized derivatives of B1 vitamin (thiamine) is first generalized and analysed in the review. It is known that at the values of pH > 7.0 the molecule of thiamine is able to undergo two-phase reaction of opening of thiazole ring with formation of anion of thiol form of thiamine and unstable tricyclic form. In the presence of oxidants in an alkaline environment a thiol form of thiamine is oxidized to thiamine disulfide, tricyclic form--to thiochrome. Oxidative transformation of thiamine molecule is promoted by phenoxyl radicals, their level can be substantially increased in animal tissues at oxidizing stress of different origin when the level of reactive forms of oxygen sharply increases and content of hemoproteins oxoferryl forms is raised. The analysis of literature data gives grounds to assume that thiamine and its hydrophobic metabolite--thiochrome--under certain conditions can perform an important antioxidant function in protection of cell structures against damaging action of peroxinitrite, nitrogen dioxide, peroxide. The presence of oxidized metabolites of thiamine and its phosphates in the cells of animals, even in minor quantities, is an established fact and, consequently, there is a possibility, that they can interact specifically with cellular structures or proteins to effect cellular processes in certain conditions.

[Existence of two different active sites on thiamine binding protein in plasma membranes of synaptosomes].

The current work is aimed at understanding the structure and functionality of thiamine binding protein (TBP) in neural cells plasma membranes. The influence of thiamine triphosphate on thiamine binding by TBP in synaptic plasma membranes (SPM) isolated from the rat brain was investigated. It was shown that thiamine triphosphate inhibits thiamine binding activity of SPM in concurrent manner (K(i) = 1.0 +/- 0.3 microM). At the same time thiamine had no effect on thiamine triphosphatase (ThTPase) activity at the concentration range 0.5-20 microM. Otherwise, ThTPase activation with the maximum at the concentration about 2.5 microM was observed. Further, the influence of classic thiamine antagonists (amprolium, oxythiamine and pyrithiamine) on both biological activities of TBP in SPM was studied. The IC50 value for inhibition of thiamine binding on SPM by amprolium comprised 50 +/- 4.0 microM. Still, this antagonist had no effect on ThTPase activity. For the oxythiamine inhibition of both TBP activities was detected. The values of IC50 were 125 +/- 28 and 1000 +/- 95 microM for thiamine binding and ThTPase activity, respectively. The values of IC50 for thiamine binding and ThTPase activity inhibition differed by more than one order of magnitude and comprised 2.2 +/- 0.2 and 43 +/- 9 microM, respectively. The obtained data indicate that the active sites on SPM responsible for thiamine binding and ThTPase activity have different sensitivity to thiamine antagonists. Our results allow us to suppose that different active protein sites are responsible for the specific binding and for thiamine phosphates hydrolysis by TBP of synaptic membranes.

[Characteristics of thiamine triphosphatase from neural cells plasma membranes].

The kinetic parameters of the ThTP hydrolysis by synaptic plasma membranes isolated from rat brain were investigated. It was shown that the ThTPase reaction pH optimum was 7.4, the apparent K(m) was 52 microM and the apparent affinity constant for Mg2+ was 1.9 mM. The comparative analysis of the indicated parameters was done for the ThTPase activity of membrane bound (the data of present work and literature data) and cytosolic (literature data) proteins. The analysis allows us to suppose that thiamine-binding protein described earlier is the single ThTPase activity carrier in neural cells plasma membranes. It was shown that the active site of the enzyme that catalyzes the ThTP hydrolysis in neural cells plasma membranes is associated with the inside membrane surface.

[Thiamine metabolism disorders in the rat brain in experimental alcoholism and a possibility of their correction by vitamin E].

The influence of the chronic consumption of alcohol on biochemical reactions of thiamine metabolism in the rat brain is investigated. It is shown that the content of thiamine diphosphate (ThDP) in the brain tissue does not change at these conditions, though there is an essential decrease in the thiamine-kinase activity. The ability of the isolated nerve terminals (synaptosomes) to absorb labelled thiamine also decreases under this condition. The specified disturbances are probably the reason for deceleration of exchange of free (uncombined with proteins) thiamine and its phosphates in nervous cells, that results in the observed reduction in activity of pyruvate dehydrogenase complex (PDC) due to inactivation by phosphorylation. Thiamine-binding and thiaminetriphosphatase activities of thiamine-binding protein (ThBP) in the structure of synaptic plasma membranes (SPM), isolated from the rat brain in various experimental groups, have been investigated. The increase, with respect to control, in the both enzymes activity in SPM, isolated from the brain of rats with chronic alcoholism has been shown. Kinetic researches testify to an increase of affinity of SPM (ThBP) for thiamine and thiaminetriphosphate in these conditions. When vitamin E was given to animals with a model of chronic alcoholism the normalization of PDC activity in nervous cells was observed, that can testify to the transient character of these changes. Inability of vitamin E to normalize biological activities of ThBP in PMS, that has been analyzed, can testify to more deep disturbances in the structure of SPM or thiamine binding protein in their structure.

[Characteristic metabolic disturbances in the rat tissues caused by long-term use of alcohol].

In the researches carried out on rats with models of chronic alcoholism and alcohol abstinence the most vulnerable to chronic action of alcohol biochemical parameters are revealed: a level of reduced glutathione (it was estimated by the content of free SH-groups in tissues), the content of thiamine diphosphate and thiaminekinase activity in a brain, the content of folic acid in the blood, the content of ubiquinone in the cardiac muscle, RNA/DNA relation in the liver. The data obtained demonstrate first of all the negative influence of alcohol on metabolism of sulfur-containing substances and processes of transmethylation. The results of our investigation have also shown that the part of metabolic changes caused by long-term usage of alcohol, can be caused by direct influence of ethanol or its metabolites on those or other enzymatic proteins or receptors, and their functions can quickly be normalized after the abolition of alcohol (NAD+ contents, alpha-ketoglutarate dehydrogenase activity and some others). More stable changes in other parts of metabolism, that were specified earlier, may be also a result of long-term alcohol consumption.

[To the 20th anniversary of the Chornobyl accident study of vitamin status and provision with micro- and macroelements of limited groups of people at different time periods since the accident at Chornobyl nuclear power plant].

Results of the study of the provision with vitamins and some micro- and macroelements of limited groups of people, who suffered from the accident at the Chornobyl nuclear power plant (ChNPP), which have been carried out by Ukrainian and Russian scientists during various periods after the accident, are generalized in the paper. Persons which participated in liquidation of the accident and lived during the accident in the territory, adjoining to Pripyat (the Kyiv region, town of Slavutich), people which worked at the object "Shelter" and ChNPP were involved in the inspection. It was noted, that in 1-4 years after the ChNPP accident in blood of liquidators the biochemical parameters displaying security of their organism by vitamins A and B1, remain lower in comparison with the same parameters in a group of relatively healthy persons which were not affected by the accident (control), that testifies to stable metabolic disturbance in the organism of people under irradiation influence. Selective inspection of the vitamin status of ChNPP and object "Shelter" personnel in 1992 has shown, that provision with vitamins C, B1, B2, B6 of the overwhelming majority of these people (67-91%) are much below the norm. Deficiency of vitamins C, B1, B6, folate and selenium is also revealed in an organism of 50-90% of women and children living in Slavutich. Deficit of vitamins in most of persons was characterized by polyhypovitaminoses, that is a combination of several group B vitamins deficiency at simultaneously low provision with selenium, and in a part of women and children--by low amount of iron. The results of long-term complex studies by groups of authors give evidence on importance and urgency of formulation and execution of International program on optimisation of nutrition, micronutrition status and health among population of affected areas in Ukraine, Bielorus' and Russia.

[Rostyslav Vsevolodovych Chahovets'. Creative activity and scientific school (on the 100th anniversary of birthday)]. / Rostyslav Vsevolodovych Chahovets'. Tvorchyi shliakh ta naukova shkola (do 100-richchia vid dnia narodzhennia).

Herein we review the main stages of life and scientific work of Rostislav Vsevolodovich Chagovets, prominent biochemist and vitaminologist, Member of the Academy of Sciences of Ukrainian SSR, professor and talanted pedagogue. As a founder of scientific school of vitaminologists and researcher in the field of muscle biochemistry, nutrition and vitamins he made a valuable contribution to development of the national and world biochemistry. This work reflects the main trends of fundamental scientific investigations and developments of vitaminological school founded by R. V. Chagovets which underlied the development of contemporary practical vitaminology.

[Intracellular localization of thiamine-binding proteins in the liver and kidneys of rats]. / Vnutrikletochnaia lokalizatsiia tiaminsviazyvaiushchikh belkov pecheni i pochek krys.

The distribution of thiamine-binding and thiamine triphosphatase activity typical of thiamine-binding proteins was studied in intracellular structures of rats liver and kidneys. It was found that the fraction of microsomes has the highest rate of specific thiamine-binding activity amide fractions of subcellular structures that was isolated using differential centrifugation in the both organs. Hydrolysis of thiamine triphosphate (pH 7.4) was also extremely active in these structures. The results of our research allow to make a conclusion that subcellular structures precipitated as fraction of microsomes (endoplasmic reticulum and vesicled parts of plasma membranes) are the sites of the most probable localisation of thiamine-binding proteins of liver and kidneys.

[Interaction of rat brain thiamine kinase with thiamine and its derivatives]. / Vzaiemodiia tiaminkinazy mozku shchuriv iz tiaminov i ioho pokhidnymy.

Participation of the enzyme which provides the phosphorylation of thiamine to thiamindiphosphate (TDP) thiaminkinase (thiaminpyrophosphokinase, KF 2.7.6.2) of rat brain in the realization of thiamine action on the syntheses of acethylcholine (AC) was studied. The thiamine and its structure analogue, which differ the nature of the radicals in the 3-d and 5-e positions of the thiazollium cycle were used: 3-[(4-amino-2methylpyrimidinyl-5)methyl]-4-methylthiazolium chloride, 3-decyloxycarbonylmethyl-4-metyl-5-beta-hydrozyethylthiazolium chloride, 3-decyloxycarbonylmethyl-4-methylthiazolium chloride. All salts in the concentrations lower then Km render active influence on thiaminkinase. The analysis of data shows the presence of the regulation site on the enzyme distinguishing from the active enzyme centre and participating in the interaction with which the hydrophobic fragments of thiamine molecule participating. The comparative studies of thiamine and above mentioned derivatives influence on the inclusion of the labelled carbon with [2-(14)C] pyruvate in acethylcholine confirm an assumption about the key-role of the thiamine interaction with thiaminkinase (meaning its phosphorilation) regarding its action on the acethylcholine syntheses, and probably, on the function of the nervous cells as a whole.

[Properties of thiamine-binding proteins isolated from rat brain, liver and kidneys]. / Kharakterystyka tiaminzv'iazuiuchykh bilkiv mozky, pechinky ta nyrok shchuriv.

The study of thiamine-binding proteins (ThBP) isolated from liver and kidneys of rats was held in order to find out the peculiarities and physiological role of the ThBP isolated earlier from the rat brain. It was demonstrated that ThBP from liver and kidneys of rats as well as ThBP from rat brain described earlier, were bifunctional: on an equal footing with ability to bind thiamine specifically, they show an ability to hydrolyse the phosphoric esters of thiamine selectively. The ThBP of these tissues (liver, kidneys and brain) didn't differ by the molecular weight, but differed by the enzymatic activities. The molecular weight of ThBP was estimated to be 100 kDa by gel-filtration; 63 kDa and 35 kDa by sodium dodecylsulfate gel electrophoresis. Specific thiamine-binding activity increases as follows: ThBP from rat brain < ThBP from rat liver < ThBP from rat kidneys.

[Basis for the historical stages for studying the biochemistry of vitamins. Noncoenzymatic mechanisms of vitamin B1]. / Osnovni istorychni etapy rozvytku biokhimiï vitaminiv nekofermentni mekhanizmy diï vitaminu B1.

Biochemistry of vitamins is one of the leading trends in the fundamental researches of A. V. Palladin Institute of Biochemistry from the moment of its foundation in 1925. The Laboratory of Vitamins Biochemistry was organised in 1994, it was reorganized into the Department of Vitamins Biochemistry in 1966, and later it was renamed as the Department of Coenzymes Biochemistry. Now the investigations at the Coenzymes Biochemistry Department headed (from 1986) by G. V. Donchenko, Corr.-Member of the National Academy of Sciences of Ukraine, are directed to estimation of vitamins A, E, B1 and PP action molecular mechanisms. Investigation of specific protein-acceptors of vitamins and their biologically active derivatives is a contemporary and effective methodological approach to the estimation of some molecular mechanisms of vitamins action on cellular metabolism. Considering the challenging theoretical and practical aspects of the further fundamental investigation development in the molecular vitaminology the following items are currently being worked in the Department last time: 1. Study of some molecular mechanisms of thiamine and vitamin PP neurotropic action. These investigations are oriented to clearing some new aspects of noncoenzymic mechanism of its influence on the nervous cell functioning both in the norm and at some nervous diseases. 2. Study of some molecular mechanisms of regulation by means of fat-soluble vitamins A, E and their specific proteins-acceptors of DNA, RNA and protein biosynthesis in the nuclei and mitochondria of actively proliferous cells. These investigations are aimed to the estimation of molecular mechanisms of fat-soluble vitamins participation in the regulation of DNA-dependent synthesis of RNA, RNA-polymerase activity, mechanism of their anticancerogenous effect, vitamin E participation in the realisation of nuclear genetic information. 3. Study of intracellular protein-receptors, which take part in realisation of vitamins and their biologically active derivatives functions in the human and animals' organism. The investigations, directed to study of a role of retinol-binding proteins in exchange of the vitamin A and in biosynthesis of DNA, RNA and proteins, the role of tocopherol-binding proteins in realisation of biological action of vitamin E in cells and thiamine-binding proteins in realisation of neurotropic action of vitamin B1 are actively developed. 4. Investigation of mechanisms of antioxidizing and antiradical biological action of vitamin D3, ecdisterone and related biologically active compounds. Basing on the fundamental researches some vitamins preparations have been created, such as "Carotin-M", "Cardiovit", "Evit-1", "Soevit", "Metovit", "Caratel'ka" and others. The results of fundamental investigation of noncoenzymic thiamine function led us to elaboration of a new hypothesis about molecular mechanism of vitamin B1 neurotropic action. According to the hypothesis the thiamine high neuroactivity is a result of existence in the nervous ending a specific mobile thiamine pool and connection thiamine metabolism with nervous cell membrane potential and acetylcholine metabolism.

[Thiamine: a mechanistic model of interaction with protein]. / Tiamin: mekahnisticheskaia model' vzaimodeistviia s belkom.

Mechanistic model of thiamine-binding protein functioning which is based on the potential role of prototropic groups and hydrophobic environment around 5-beta-hydroxyethyl substituent of ligand has been proposed. As a model the chemical transformations of thiamine and its structural O-acyl substituted analogues in the presence of ferricyanide and phosphatic buffer in pH range 7,2-7,8 were investigated. The oxidation to the thiochrome and thiochrome derivatives is first order in substrate and ferricyanide concentrations. It is found that the reciprocal of the pseudo-first-order rate constant increases in ferrocyanide concentration at the constant oxidant concentration. Rate constants and partition ratios for reaction of thiamine, O-benzoylthiamine, O-(4-nitrobenzoyl)thiamine, O-(2-norbornoyl) thiamine, O-(1-norbornoyl)thiamine, O-(1-adamantoyl) thiamine, O-(2-adamantoyl) thiamine, O-(5-methyl-1-adamantyl)acetylthiamine, O-(2-adamantyl)acetylthiamine, O-(1-adamantyl)acetylthiamine were determined. The acceleration effect of hydrophobic fragment of O-acyl substituent is attributed to the formation of neutral tricyclic form in the step followed by electron transfer to ferricyanide. Mechanistic implications for possible transformation of thiamine in neutral tricyclic form at interaction with thiamine-binding protein are discussed.

[Provision of residents of the city of Kiev with vitamins C and B1. Effectiveness of a complex vitamin-mineral preparation in preventing spring vitamin deficiencies]. / Pbespechennost' zhitelei g. Kieva vitaminami C i B1. Effektivnost' kompleksnykh vitaminno-mineral'nykh preparatov v profilaktike vesennikh gipovitaminozov.

The investigation was conducted on provision with vitamins C and B1 of Kyiv inhabitants limited contingent at spring period and efficiency of complex vitamin-mineral preparations in normalisation of the vitamins level in blood of human-subjects. The deficit of vitamin C in 54% and vitamin B1 in 18.5% of the investigated people was revealed. Supradin gave the best results among rest preparations ("Centrum", "Vitrum", "Duovit", "Multi-Tabs") in the normalization of the level of vitamin C and biologically-active form of thiamine (thiamindiphosphate) in the blood of investigated people.

[Interaction of thiamine with rat brain synaptosomes]. / Vzaimodeistvie tiamina s sinaptosomami mozga krys.

Thiamine has been shown to be bound specifically by a synaptosomal plasmatic membrane and transported inside to the nervous ending. Apparent K[symbol: see text] and Km for processes of binding and transport have been determined as equal 2.34 +/- 0.55 MKM and 3.92 +/- 1.3 MKM, respectively. The thiamine uptake by the isolated nervous endings (synaptosomes) at its physiological concentration is reduced in presence of metabolic inhibitors and partially depends on Mg2+ and Ca2+ ions, that can testify about the interrelation between endogenic thiamine phosphorilation and its transport through the membrane. Thiamine binding with synaptosomes is inhibited by ouabain and neurotoxins such as, latrotoxin and most significantly--with veratridin; tetrodotoxin fail to be efficient practically. In the conditions of synaptic membranes depolarisation their ability to bind thiamine is reduced and output of already uptaken with synaptosomes thiamine is observed.

[Blood vitamin levels in various population groups in the Ukraine suffering from sequelae to the accident at the Chernobyl power plant]. / Bmist vitaminiv u krovi riznykh grup naselennia, shcho poterpilo vnaslidok avariï na ChAES.

The levels of vitamins in the blood of persons who suffered from the catastrophe at Chernobyl NPP subject to medically treatment at Kiev clinics at different time periods have been studied. Polyhypovitaminosis has been detected in all the patients groups examined, especially in persons with the diagnosis of acute radiation sickness. The hypovitaminosis status in the organism is regulated by means of an adequate vitamin therapy. The scientifically substantiated vitamin therapy and vitamin prophylaxis are proposed to be performed for the population of Ukraine affected by the consequences of the Chernobyl catastrophe.

[Inactivation of yeast pyruvate decarboxylase in the presence of substrate and quinone electron acceptors]. / Inaktivatsiia drozhzhevoi piruvatdekarboksilazy v prisutstvii substrata i khinonovykh aktseptorov élektronov.

The rate constants of paracatalytic inactivation of pyruvate decarboxylase in the presence of 1,4-naphthoquinones and 1,4-benzoquinones are determined by redox potentials of the oxidant. The logarithm of k2 depends hyperbolically on the redox potential of quinone E0(Q/Q-.) with the coefficient of proportionality which approximates 8.4, The absence of considerable deviations in this correlation for the oxidants of different structures with closed values Eo(Q/Q-.) indicates that the enzyme produces no additional steric barrier.

[The interaction of pyruvate decarboxylase with the quinone-ferricyanide oxidative system]. / Vzaimodeistvie piruvatdekarboksilazy s okislitel'noi sistemoi khinon--ferritsianid.

Inactivation of yeast pyruvate decarboxylase in the presence of substrate and oxidative system containing substituted quinone and ferricyanide has been investigated. It was established that ferricyanide at pH 5.2-6.4 can prevent irreversible inactivation of the pyruvate decarboxylase caused by the concerted action of pyruvate and substituted quinone. The influence of ferricyanide which depends on the redox potential of the substituted quinone is decreasing in a series tetramethyl-p-benzoquinone, trimethyl-p-benzoquinone, 2-methyl-5-isopropyl-p-benzoquinone. It is supposed that the effect of the oxidative system partially converting the nonoxidative to oxidative function of pyruvate decarboxylase is attributed to the oxidation of active acetaldehyde by substituted quinone and reaction of resultant semiquinone radical with ferricyanide.

[The neural activity of thiamine: facts and hypotheses]. / Neiroaktivnost' tiamina: fakty i gipotezy.

A review of some experimental results as to identification of the specific role of thiamine in functioning of nerve cells is presented. Failure to attribute high neuroactivity of thiamine considering only its known biochemical function as a coenzyme precursor of some key Enzymes of the carbohydrate metabolism has formed conceptions existence of non-coenzyme functions in this vitamin which are realized in nerve cells. The Investigation of this thiamine function has been developing mainly in two principal directions the study of participation of biologically active thiamine derivatives is functioning of the excited membrane ion channels and the study of their role in the synthesis and metabolism of acetylcholine. Taking into account analysis of their own data and those available in literature, the authors formulate a hypothesis which attributes high neuroactivity of thiamine not to the existence of a certain function in the nerve cells new for this vitamin but only to the peculiarities of the structure-functional organization of the cells the existence of excited membrane, and interdependence between the cellular metabolism and transport of loss via the membrane, which underlies regulation of the synthesis, release, capture and catabolism of neurotransmitters.