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Biomedical subjects

A D Makarov

Publications and source records attributed to A D Makarov.

At least 19 recordsLinked to original sources
PubMed1994

[Humoral autoimmunity markers in autoimmune endocrine diseases].

To clarify the value of autoantibodies as risk factors of complications in various endocrine abnormalities, the incidence of autoantibodies to thyroid microsomal antigen (ATMA), thyroglobulin, and the surface antigens of the rat islet, adrenal cortex, adenohypophyseal cells and human skin fibroblasts was studied in patients with insulin-dependent mellitus (IDDM), at the onset of the disease and during one-year insulin therapy, non-insulin-dependent diabetes mellitus (NIDDM), Hashimoto thyroiditis, Graves' disease, diabetes associated with thyroidal dysfunction, euthyroid polynodular goiter, Schmidt and polyglandular syndromes and in the population. The antibodies were determined by ELISA. Polyclonal activation of the immune system was found in all abnormalities, except in polyglandular in children. The proportion of patients with more than one type of antibodies was minimal (26.4%) in IDDM and maximal (62.0%) in Graves' disease. Among IDDM patients, polyclonal activation of the immune system was observed more often in women than in men (48.5 vs 8.5%). The persistence of antibodies to fibroblasts in IDDM patients was associated with the development of vascular complications. The latter were observed in 4 of 7 patients who had these antibodies during a year and in none of negative patients. Thus, fibroblast antibodies may have a predicative significance for the development of late diabetic complications. The highest prevalence of these antibodies was discovered in Graves' disease (37.9%) wherein the antibodies may be involved in the development of exophthalmus and pretibial mixedema. Thyroidal dysfunction developed in all IDDM patients with ATMA preserved during a year and in none ATMA-negative patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

[The special reaction of photophosphorylation using epsilon ADP--a fluorescent analog of ADP].

Photophosphorylation of epsilon ADP in a chloroplast synthetase system reconstituted with CF1 or with CF1 modified by covalently bound epsilon ADP has been studied. The reconstitution of EDTA-treated chloroplasts with CF1 restores the photophosphorylating activity to about 90%. When the CF1 modified by covalently bound epsilon ADP is used for reconstitution the photophosphorylating activity of EDTA-treated chloroplasts is restored to 37%. Based on the results of a photochemical study of the chloroplast ATP-synthetase system reconstituted with CF1 with covalently bound epsilon ADP it may be assumed that the substrate, adenine, participates in proton translocation to inorganic phosphate in the active center of the coupling enzyme during photophosphorylation.

Adenosine Diphosphate↗
PubMed1981

[Adenylate kinase activity of phycobilisomes from the blue-green algae Microcystis aerogenosa].

The phycobilisomes (PBS) from the blue-green algae Microcystis aerogenosa was found to possess the adenylate kinase activity. The enzyme activity of PBS is kept for 2 weeks, reaching its maximum on th 2nd-4th day after PBS isolation from the cells, and is retained after passage of freshly isolated PBS through a column with Sephadex G-25. The adenylate kinase activity of PBS is thermostable, depends on the protein concentration in the sample, undergoes activation by white light and is inhibited by glutaric aldehyde. The enzyme activity is presumably determined by the components of the low molecular weight protein fraction of non-pigment origin, which are constituents of PBS.

Adenylate Kinase↗
PubMed1981

[Role of the pterin component in light and dark oxygen consumption by chloroplasts].

The effects of ferredoxin and the pterin component from pea chloroplasts on oxygen consumption by pea and spinach chloroplasts in the dark and in the light were studied. In the absence of the pterin component the illuminated chloroplasts from both sources weakly reduce oxygen. An addition of the pterin component produces different effects on oxygen consumption by pea and spinach chloroplasts: the former efficiently reduce oxygen after addition of a single pterin component, while the latter require the presence of ferredoxin as well. The data obtained suggest that in pea chloroplasts there exists a ferredoxin-independent pseudocyclic electron transport mediated by pterin. In spinach chloroplasts this electron transport is ferredoxin-dependent. In the presence of pterins the chloroplasts are capable of carrying out dark reduction of O2, using NADPH and H+ as electron donors.

Chloroplasts↗
PubMed1980

[Properties of epsilon-ATP hydrolysis by CF1-ATPase from pea chloroplasts].

The ATPase activity of CF1 isolated from pea chloroplasts with epsilon-ATP, the fluorescent analog of ATP and ATP used as substrates, in the presence of Mg2+, Ca2+ and sodium sulfite (stimulator of the ATPase activity) was studied. The rate of epsilon-ATP hydrolysis in the presence of Mg2+ is nearly two times as low as that of ATP; an addition of sodium sulfite to the reaction mixture increases the reaction rate without changing the above ratio. The rate of Ca2+-dependent hydrolysis of epsilon-ATP is rather low as compared to that in the presence of Mg2+. epsilon-ADP is a competitive inhibitor of Mg2+-dependent ATPase reaction and inhibits this process in the presence of Ca2+, the inhibition being of a mixed type. Modification of CF1 by covalent binding of epsilon-ADP results in a 70-80% decrease of the Mg2+-dependent ATPase activity, the Ca2+-dependent ATPase activity is changed only insignificantly thereby. The differences in the activation of ATP and epsilon-ATP hydrolyses by Ca2+ and Mg2+ can be accounted for by the existence of two sites in the active center of CF1, which are specific for Mg2+ and Ca2+, respectively. It is concluded that the binding of epsilon-ADP occurs in the Mg2+-dependent ATPase site of the active center.

Adenosine Triphosphatases↗
PubMed1980

[Evaluation of changes in free energy of proteins and biomembranes under pH-induced conformational transitions. Coupling membranes of peak chloroplasts].

It was shown that changes in the free energy during pH-induced conformational transitions can be calculated from the buffer spectrum of the biopolymer. These changes are similar to those of the chemical potential of cooperatively protonating groups (delta Go = 2,3 RT (pKt--pKi)Nt) and can be determined independently for each transition of the complex object. Consequently, in case of biomembranes with the ionic strength greater than or equal to 0,1 it is possible to determine not only the maximal efficiency of each transition according to the formula magnitude of delta Go congruent to 2,3 RTNt, but also that of the membrane component which initiates the given transition. Thus, a study of the photo-dependent buffer spectrum of the coupling membranes of chloroplasts showed that in the membrane the ATPase complex performs a reversible conformational transition within the pH region of photophosphorylation with the energy of 100--130 kcal/mol for the coupling factor or 190--260 cal/mol for the chlorophyll.

Chloroplasts↗
PubMed1978

[Isolation and properties of CF1 ATPase chloroplasts with changed submolecular structure].

An isolation procedure is worked out and properties are studied of CF1 ATPase from chloroplasts with changed submolecular structure. The enzyme, isolated by chlorophorm treatment, produced Ca-dependent ATPase activity in water solution. As compared with the enzyme isolated by well known Lien and Racker method, the enzyme preparation obtained is slightly activated by heating, is not activated by trypsin and has a lesser ability to recover ATP synthesis in EDTA-treated chloroplasts. Purification on DEAE-Sephadex produced the enzyme preparation free of delta-subunit. Chlorophorm treatment is suggested to change submolecular protein structure, in particular, loosening of the link of delta-subunit with other enzyme subunits. The data obtained suggest that delta-subunit participates in the binding of CF1 ATPase with chloroplast membrane.

Cell Membrane↗
PubMed1978

[Buffer capacity of polyproton substances].

Mathematical analysis of protolytic properties of a polyelectrolite with arbitrary set of stepwise dissotiation constants is carried out, based on disintegration of summary titration curves and buffer capacity for basic functions. It is demonstrated, that in some cases (for example, investigation of biomembranes and their components) simplified disintegration variants can be used. Buffer titration curve of biopolymers and biomembranes is a "buffer spectrum", the position of bands on the pH scale, their intensity and half-width being determined by the nature of the object (the quantity and quality of hydrophilic groups and the set of its conformation states). Sharp peaks of the buffer spectrum correspond to the conformation transition of the object, and their half-width on the pH scale determines the cooperative degree of each conformation transition. The mathematical analysis described is not specific to the formation of polyprotonic complex, and it can be used in investigation of the complex formation with any monodentant ligand. It is concluded that the method described can be used in the investigation of complex biomembranes and different processes, in which these membranes participate.

Buffers↗
PubMed1976

[Interaction of adenine derivatives with chloroplast membranes].

Structural changes of chloroplast fragments result in increased adsorption of adenine derivatives. The nativity of membranes is essential for AMP adsorption. Chloroplast fragments, containing CF1, adsorb adenine and adenosine by 30% and ADP by 50% more than the fragments, devoid of the enzyme. It is assumed that lipids may act as sorbents during nucleotides interaction with the chloroplast membrane.

Adenine↗
PubMed1976

[Some peculiarities of the reaction kinetics of ATP hydrolysis by Ca2+-dependent ATPase of chloroplasts].

The dependence of the reaction rate of ATP hydrolysis by CF1-ATPase of chloroplasts on the substrate (CaATP) concentration is of complex nature. It is assumed that such dependence may be due to either conformational changes of the enzyme during the increase in CaATP content in the reaction medium, or consecutive binding of the substrate to its active sites, differing in their affinity to the substrate of the reaction.

Adenosine Triphosphatases↗
PubMed1976

[Study of the kinetics and mechanism of ATP hydrolysis by soluble ATPase of the chloroplasts (CFl) in the presence of Mg2+ ions].

A kinetic study of ATP hydrolysis by soluble ATPase of chloroplasts (CF1) was made. At low concentrations of MgCl2 a linear increase of the reaction rate was observed during the increase in the ATP concentration up to 1 mM. At high concentrations of MgCl2 the dependence was of a more complicated nature. At MgCl2 concentrations lower than 0.1 mM the reaction approached second-order kinetics with respect to Mg2+; the increase in MgCl2 concentration resulted in a decrease of the reaction order. It is assumed that MgATP is the "true" substrate and MgADP the "true" inhibitor of the reaction. A reaction mechanism of ATP hydrolysis is postulated.

Adenosine Triphosphatases↗
PubMed1976

[Adenylate kinase of plants. Properties of adenylate kinase of pea leaves].

The properties of adenylate kinase in 2 ADP in equilibrium ATP + AMP reaction have been studied. The dependence of the enzyme activity on medium pH, protein concentration, substrates, Mg++ ions, AMP, adenine and adenosine has been also investigated. pH optimum is found to be 8.5 for forward reaction and 8-9--for the reverse one. The Michaelis constants are as follows: for ADP--1.17-10(-4) M, for ATP--3.33-10(-4) M at 24 degrees C, in 50 mM tris-HCl pH 7.6. The optimal ratio, Mg++ ions/substrates (ADP, ATP + AMP), is 1:2. The chelates of adenine nucleotides with Mg++ ions are proved to be "true" reaction substrates. Unlike adenine and adenosine, the product of AMP reaction inhibits adenylate kinase activity. It is concluded that the properties of adenylate kinase in plants are similar to those of animals and humans (moikinase).

Adenylate Kinase↗
PubMed1976

[Pterin-protein complex and ferredoxin as possible components of a molecular complex in photosystem I].

Properties are studied of pterin-protein complex (PPC), possible precursor of ferredoxin in electrone transport chain PS-I. PPC is shown to form chelate complex with Fe ions which are capable to activate the process of light reduction of NADP+ by chloroplasts in the absence of ferrodoxin. A possibility of dark reduction of NADP+ with the participation of light pre-activated PPC is found. Two-step scheme of electrone transport from P700 to ferredoxin is supposed. The data obtained indicate that one of sites of electrone transport into interior part of tilakoid is located on the reduction side of PS-I. An additional possibility of NADP+ reduction with the participation of PPC-Fe in vivo is suggested.

Chloroplasts↗
PubMed1976

[Participation of the iron-containing pterine-protein complex in NADP reduction and electron transport].

A factor of protein nature, containing pteridines and iron ions was isolated from pea leaves. The compound was shown capable of activating NADP reduction during chloroplasts illumination in the absence of ferredoxin. The compound was termed "NADP-reducing factor" (NRP). Freshly isolated NRF in combination with the protein possessing the NADP-reductase activity, reduces NADP in the dark. The factor accepts the electron from the reaction site of the first photosystem and activates hydrogen liberation in the systems, containing hydrogenase. A possibility of an existence of an additional site of NADP reduction in chloroplasts is discussed.

Chloroplasts↗
PubMed1976

[Structure of electrochemically reduced adenine nucleotides. Their interaction with inorganic phosphate].

The stable reduced form of adenosine phosphates has probably cyclic or dimeric structure of the type: adenine "head"--phosphate "end". Inorganic phosphate produce a stabilyzing effect on reduced adenosine due to a strong ionic interaction with the amino group. In the case of reduced ADP, inorganic phosphate can incorporate into adenine nucleotide, which oxidation results in the formation of small amounts of ATP. A scheme of possible mechanism of this process is given.

Adenine Nucleotides↗