Isolation and properties of malate dehydrogenase from Meso-and thermophilic bacteria

A scheme of purification of malate dehydrogenase from Macromonas bipunctata strain D-405 and Vulcanithermus medioatlanticus DSM 14978^T was developed. This scheme was used to obtain electrophoretically homogeneous enzyme preparations of the mesophilic bacterium M. bipunctata (specific activity, 26.9 ± 0.8 U/mg protein; yield, 10.9%) and the thermophilic bacterium V. medioatlanticus (specific activity, 5.0 ± 0.2 U/mg protein; yield, 19.2%). Using these high-purity enzymatic preparations, the physicochemical and regulatory properties of malate dehydrogenase were studied and the differences in kinetic characteristics and thermal stability of the preparations were determined.     

The effect of synthetic proteinase inhibitors of the level of human recombinant proinsulin production, secreted by a genetically engineered strain of Bacillus subtilis

Influence of O,O,-diethyl-1-(N-alpha-hydrohexafluoroisobutyryl)amino-1- methylpropylphosphonate and O,O-diisobutyl-1-[2-(ethoxycarbonyl)aminoperfluoroprop-2-yl] -1- methylpropylphosphonate on the level of production of human proinsulin secreted by a genetically engineered culture Bacillus subtilis AJ 73 (pBINS1.0.) has been studied. The above phosphonates, being non-toxic for microorganisms, reduced degradation of proinsulin by serine proteinases.     

Cyclic nucleotide phosphodiesterase of the olfactory membrane in rats: its distribution and possible connection with the estradiol receptor

In the rat olfactory tissue the existence of soluble and membrane-bound forms of cyclic nucleotide phosphodiesterase (PDE) with quite similar kinetic parameters was demonstrated (KM = 220 and 200 microM, VMaX = 10 and 7 nmoles cAMP/mg protein per minute, respectively). 17 beta-estradiol (10(-7)-10(-5) M) decreased the soluble PDE activity by 25%, whereas non-hydrolysable GTP analogue (Gpp (NHp)) abolished their effect. On the other hand, this analogue in a dose-dependent manner inhibited the specific binding of 3H-estradiol to cytosolic receptors. The data indicate possible functional interrelations between the cytosolic estradiol receptors, GTP-binding proteins and PDE in the olfactory tissue which is a target organ for steroid hormones.     

Effect of a beta 2-blocker on the adrenergic receptors of lymphocytes in hypertension

A short-term effect of propranolol on beta 2-adrenoceptor density in mononuclear lymphocytes was studied in 15 male patients with essential hypertension. According to receptor density alterations the hypertensive subjects were divided into two groups. In the first group lymphocyte beta 2-receptor density increased substantially (3 times, on the average). Propranolol had a weak antihypertensive effect in this group, with the initially low plasma renin activity remaining unchanged after the treatment. The patients of the second group, on the contrary, revealed features of sympathetic hyperactivity and a decrease (2 times on the average) in lymphocyte beta 2-receptor density. Propranolol administration caused a decline in the initially normal or elevated plasma renin activity as well as in systolic arterial blood pressure and heart rate.     

Fe-Si biominerals in the Vilyuchinskie hot springs, Kamchatka Peninsula, Russia.

The micromorphological structure of microbial mats (biomats) from the hot springs of the Vilyuchinskaya hydrothermal system, Kamchatka Peninsula, Russia, were investigated. The Vilyuchinskie hot springs had a discharge temperature of 55-56 degrees C and Na-Ca-HCO3-type waters rich in silicic and boric acids. Water and biomats had high concentrations of Fe, Mn, Sr, and As. Enumeration of total bacterial abundance (TBA) demonstrated a low density of bacterial populations. However, the fractions of metabolically active bacteria and respiring iron-oxidizing bacteria in the hot-spring water were high, comprising 68 and 21% of TBA, respectively. Scanning electron microscopy equipped with an energy dispersive X-ray spectrometer (SEM-EDX) showed that unicellular rod-shaped bacteria about 5-microm long predominated in the brown biomats. The mineral capsules of these bacteria contained large amounts of Fe and Si. Extracellular and intracellular particles were observed by transmission electron microscopy. Fe-oxidizing bacteria were isolated from the biomats on agar plates with selective medium. Therefore, it can be concluded that microorganisms inhabiting the biomats of the Vilyuchinskie hot springs are essential for the deposition of Fe-minerals at neutral pH.     

Comparative characterization of microbial communities in two regions of natural oil seepage in Lake Baikal

Microbial communities and hydrocarbon contents have been studied in two regions of natural oil seepage in Lake Baikal: (1) opposite the Bol’shaya Zelenovskaya River mouth (studied previously) and (2) near Cape Gorevoi Utes (discovered in 2005). The abundance of both heterotrophic and hydrocarbon-oxidizing microorganisms is significantly higher in water samples from the first region, where the oil is biologically degraded. In the surface soil layer at stations located in the immediate vicinity of oil seepage site, the abundance of n-alkane-oxidizing microorganisms reaches 2000 cells/ml, and that of oil-oxidizing microorganisms reaches 2600 cells/ml. In water samples from near Cape Gorevoi Utes, the abundance of these groups of microorganisms does not exceed 190 and 500 cells/ml, respectively.     

Study on the Lake Baikal microbial community in the areas of the natural oil seeps

We studied the composition of a natural microbial community, the distribution of different groups of microorganisms (including those able to degrade oil hydrocarbons) within the areas of natural oil seeps in the Lake Baikal. It was revealed that, in the bottom sediments, the oil-degrading microorganisms dominating the community have included the bacteria of g. Bacillus, while in the water column, dominating microbes are presented by species of genera Rhodococcus Pseudomonas, and Micrococcus. Under the conditions of the model experiment, the potential activity of Baikal microbes towards utilization of n-alcanes has been assessed. Under such conditions it was shown that the concentration of n-alcanes decreases to 60% during 20 days of the experiment (the initial oil concentration was 0.5 mg/l, i.e., ten maximal permissible concentrations, MPC).     

Isolation, Purification, and Properties of Malate Dehydrogenase from Sulfur Bacterium Beggiatoa leptomitiformis

Malate dehydrogenase (E.C. 1.1.1.37) from the bacterium Beggiatoa leptomitiformis was isolated and purified 123-fold using a five-step purification procedure including the enzyme extraction, ammonium sulfate protein fractionation, gel filtration, ion exchange chromatography, and gel chromatography. The enzyme was homogenous according to the electrophoresis data; its activity was 20.43 U/mg protein. This malate dehydrogenase is a homotetramer (Mr = 172 kDa). The catalytic and thermodynamic properties, as well as the analysis of the published data suggest that the tetrameric structure of the enzyme allows it to participate in constructive metabolism supplying the cell with organic acids as a source of carbon.