O. V. Yagodina

Inorganic Phosphate Stimulates the Toxic Effects of Tl + in Rat Liver Mitochondria

We studied action of inorganic phosphate (Pi) on toxic effects of Tl+ in isolated rat liver mitochondria. This is a convenient model to study the toxicity of heavy metals. Pi markedly retarded contraction of energized mitochondria swollen in the TlNO3 medium and even stronger stimulated swelling and state 4 of succinate‐energized mitochondria in the TlNO3 medium. A valinomycin‐induced decrease of K+‐diffusion potential was also accelerated by Tl+ in the presence of Pi. The mitochondrial permeability transition pore in the medium containing Ca2+, TlNO3, and nitrates of univalent cations was distinctly stimulated by Pi. However, Pi did not affect both the Tl+‐stimulated swelling of nonenergized mitochondria in the TlNO3 medium and swelling of energized mitochondria in the Tl acetate medium. Respiration stimulated by 2,4‐dinitrophenol and monoamine oxidase activity of energized mitochondria were not affected by Tl+ regardless of the presence of Pi. We suggested that stimulation by Pi of toxic action of Tl+ in mitochondria and cells could be due to even greater enhancement of uncoupling of mitochondria as shown by an additional increase of swelling and state 4, and in the greater probability of opening of MPTP in the presence of Pi and Ca2+.

The main factors of monoamine biosensor selectivity increasing

The influence of the main factors of biosensor selectivity on monoamine determination have been studied. In the composition of new biosensors amine oxidases (AO) from different sources were used: mitochondria AO from pig and rat liver, and AO from Methanosarcina barkeri 27 bacterial strain. Enzyme preparations of different purification degree, and immobilized in different ways have been studied. Potentiometric electrodes, gas-sensing electrodes, and colorimetric sensor were used as the analytical detectors in the designed biosensors. New methods for the individual determination of monoamines and for the detection of their sum in the sample have been worked out.

Enzymological characteristic of monoamine oxidase from the visual ganglia of the Pacific squid Todarodes pacificus

The study of catalytic properties of mitochondrial monoamine oxidase (MAO; monoamine:О2 oxi� doreductase, deaminating; EC 1.4.3.4), which main� tains physiological level of mediators in the presynap� tic nerve terminal, is of general biological interest and a great importance for enzymology, in particular, for characterizing redox enzymes. The biological role of MAO is associated with the regulation of the level of mediators in nerve structures and, therefore, with dif� ferent functions of the nervous system, which is con� firmed, in particular, by experimental and clinical data on the use of MAO inhibitors [1]. The study of the sub� strate specificity and multiplicity of MAO forms in the central nervous system of different animals will proba� bly provide an opportunity to differentially determine the functional role of MAO in neural processes. The majority of available papers in this field are devoted to studying MAO of terrestrial vertebrates, whereas MAO of aquatic animals has been studied quite insuffi� ciently. It was established that neural tissues of marine invertebrates contain a relatively high MAO activity as compared to other organs [2, 3]. Monoamine oxidase activity was detected in the visual ganglia, which fulfill the function of the central nervous system, of some cephalopods, such as octopuses Octopus vulgaris [4], Eledone moschata [5], and Eledone cicchosa [6] and squids Loligo forbesi [7], Loligo pealei [8], and Berry� teuthis magister [9]. Although over 350 squid species are known in the World Ocean [10], the monoamine oxidase activity of visual ganglia has been studied so far only in a few of them [7–9], which is possible caused by difficulties in obtaining biological material. Almost all papers devoted to the MAO of visual ganglia of squids contain only qualitative results. The list of kinetically studied enzymes with enzymological parameters of substrate–inhibitor specificity is quite scanty [8]. The substrate and inhibitor analyses of monoamine oxidase activity of visual ganglia of the Pacific squid Todarodes pacificus were undoubtedly of interest. The kinetic parameters of enzymatic deamination of tyramine, serotonin, benzylamine, histamine, tryptamine, and β�phenylethylamine as well as bimo� lecular rate constants for the interaction of inhibitors deprenyl and chlorgilin with the enzyme were calcu� lated. It should be noted that this was the first work to study the catalytic properties of MAO from the visual ganglia of this commercially important squid species.

Analysis of the effect of the polyprenol preparation ropren and the choline alphoscerate preparation gliatilin on the membrane-bound and soluble forms of cholinesterases and monoamine oxidase of rat brain and serum in the tetrachloromethane model system of hepatic encephalopathy.

33 With regard for an increased interest to designing new therapeutic and prophylactic tools of plant origin containing a broad spectrum of biologically active compounds, broadening the spectrum of their physiological efficacy is a relevant problem [1]. One of such preparations, isolated from the neutral part of needles of pine and spruce, is ropren—a representative of the group of polyprenols (long-chain polyisoprene alcohols) [2, 3]. It was demonstrated earlier that ropren exhibits immunomodulatory properties and stimulates humoral response of the organism to phagocytosis, which may be successfully used for treating various infectious, allergic, and autoimmune diseases [2, 3]. In addition, these are grounds to assume that ropren displays certain cerebroprotective and hepatoprotective effects [4]. For this reason, it was of interest to use the hepatotropic model of hepatic encephalopathy induced by injecting animals with tetrachloromethane (carbon tetrachloride, CCl 4 ) [5] for comparing the effects of the polyprenol preparation ropren and the choline alphoscerate preparation gliatilin, which has an integrated effect on neuronal function [6]. Such a comparison may be a key stage of targeted screening of physiological efficacy of biologically active polyprenol compounds. However, when the tetrachloromethane model used, it should be taken into account that tetrachloromethane is a strong hepatotoxic agent, mostly due to a pronounced membranotropic effect [5]. It can be easily understood how a hydrophobic solvent, such as CCl 4 , can affect the lipid components of the membrane [7]. For this reason, the problem of establishment of the role of biologically active preparations in physiological processes may also be related to analysis of their membranotropic effect. The method that most adequately corresponds to the goals of this study is enzymatic analysis, due to its versatility and high sensitivity [8].

Amino oxidase activity of hepatopancreas preparations from the octopus Bathypolypus arcticus

39 The liver of different animals contains two types of amine oxidases (AOs)—monoamine oxidase (MAO, monoamine: О 2 oxidoreductase, deaminating, EC 1.4.3.4) and diamine oxidase (DAO, diamine: О 2 oxii doreductase, deaminating, EC 1.4.3.6) at different ratios, with the activity of DAO being much lower than the activity of MAO [1]. Liver mitochondrial MAO has a pivotal function: it is involved in the removal of toxic amines entering the bloodstream from the digess tive organs. An increased interest to this AO type is associated with other possible biological functions of the enzyme, including the formation of compounds with intrinsic biological activity, participation in tissue respiration and oxidative phosphorylation, and reguu lation of the activity of membraneebound mitochonn drial enzymes [1, 2]. The majority of studies were perr formed with the enzyme of terrestrial mammals [1–3]. At the same time, studies of the catalytic properties of MAO from tissues of cephalopods, such as octopus Eledone moschata [4], Eledone cirrhosa [5], and Octoo pus vulgaris [6, 7] revealed its peculiar properties. Although the order Octopoda numbers approximately 200 living species inhabiting the world ocean [8], the monoamine oxidase activity of the hepatopancreas, an organ that combines the functions of the liver and the pancreas, has been studied so far only in Octopus vull garis [6, 7], which is possibly due to the difficulty in obtaining the biological material. The key characteriss tic of octopuses is their ability to adapt. It was assumed that mollusks inhabiting cold water have special metaa bolic adaptations to low temperature [8]. It should be noted that the octopuses studied earlier [4–7] belong to the boreallsubtropical type and dwell at different depths varying from shallows to 100–150 m. Is was of interest to determine the characteristics of the functionally important enzyme MAO of the hepatopancreas of the deepsea arctic–boreal cephaa lopod species—octopus Bathypolypus arcticus (Prosch, 1849), which is found at depths up to 1000 m. This is the first study to compare the substrate and inhibitor specificity of MAO from hepatopancreas of this octopus species, which differs from those studied earlier not only by the habitat (this is an obligatory bottom species that lost the relationship to the land) but also by the small size and internal structure (the absence of the ink sac). The study was performed with mature B. arcticus octopuses caught during the expee dition to the southeast coast of the Barents Sea in summ …

Sensitivity of the mink (Mustela vison) liver monoamine oxidase to isoquinoline alkaloids.

MAO. Note that the inhibitory specificity of mink MAO is virtually unstudied. Only one [11] of the available scarce papers on the catalytic properties of this enzyme reports its sensitivity to two acridine derivatives. Analysis of the effects of benzo[c]phenanthridine alkaloids (sanguinarine and chelerythrine), the diisoquinoline alkaloid berberine, and the drugs Ukrain and Sangviritrin on the mink ( Mustela vison ) liver MAO activity, conducted for the first time, is of doubtless interest for expanding the biochemical studies into the properties of enzymes of domesticated fur-bearing animals. Mitochondrial fragments of the American mink ( M. vison Schreb.) liver were the source of MAO. The liver was excised from mature 2-year-old male minks with a weight of 1.5‐1.7 kg kept under standard conditions in the Kondopoga State Fur Plant [12]. The animals were euthanized by decapitation. The mitochondrial membranes were isolated from tissue homogenates partially purified from the ballast protein by extraction in 0.0075 M potassium phosphate buffer pH 7.4 [13]. The mitochondrial fragments were obtained by freezing at ‐20 ° C with subsequent centrifugation and stored frozen until used. The protein content, determined by biuret method, amounted to 17 ± 2 mg/ml. MAO activity was determined spectrophotometrically (at 420 nm) according to the amount of ammonia formed over 30 min in the enzymatic reaction of oxidative deamination of the monoamines— tyramine hydrochloride, benzylamine hydrochloride, and β -phenylethylamine hydrochloride (Sigma, United States)—with serotonin creatinine sulfate (Reanal, Hungary) according to the modified Conway method with subsequent nesslerization [13]. The samples (final volume, 2.5 ml) contained fragments of mitochondrial membranes in an amount corresponding to approximately 1 mg protein, 0.5 ml of inhibitor (tested preparation) at a specified concentration or 0.5 ml of water (in control experiments), 0.5 ml of 0.01 M phosphate buffer pH 7.4, and 0.5 ml of a substrate at a specified concentration (1 mM tyramine, tryptamine, benzy

Catalytic Properties of Monoamine Oxidase from the Lamprey Lampetra fluviatilis Liver

270 The substrate-inhibition specificity of liver monoamine oxidase (MAO) has been studied in mature lampreys ( Lampetra fluviatilis ) of both sexes. The catalytic properties of the enzyme have been found to resemble those of the classic mammalian MAO: the enzyme deaminates tyramine, tryptamine, serotonin, and benzylamine, but not histamine; it is sensitive to proflavin, the well-known type A MAO inhibitor; and is not inhibited by 10 ‐2 M semicarbazide. It is assumed that the MAO from the lamprey liver, as well as liver MAOs of other hydrobionts (squids and fish), has several substrate-binding sites or is represented by several isozymes. The observed specificity of the inhibitory effect of proflavin confirms this assumption. The detoxicating activity of the lamprey liver MAO is low, which may be accounted for by the anatomical and physiological characteristics of the digestive system of lampreys. The enzyme monoamine oxidase (monoamine:O 2 oxidoreductase (deaminating); EC 1.4.3.4) plays the key role in the adrenergic neurotransmitter metabolism and implements an important barrier function on inactivation of biogenic amines [1‐3]. Although this enzyme was discovered more than 80 years ago, its functional role remains obscure. It was established that, in the majority of animals, this enzyme is highly active in the liver and brain [1]. To date, the catalytic properties of liver MAO have been studied predominantly in representatives of higher terrestrial animals. In numerous representatives of the most ancient class of contemporaneous aquatic vertebrates, Cyclostomata, only the MAO from the lamprey Lampetra japonica brain [4] and the hagfish Eptatretus burgeri brain [5‐7] have been studied. Notably, the activity of lamprey liver MAO has not been studied earlier.