The structure and activity of fungal lipases in bile-salt solutions

The changes in the structure and catalytic properties of fungal lipases (Candida rugosa, Rhizomucor miehei, Mucor javanicus) were investigated in micellar solutions of bile salts that differ in their hydrophilic–lypophilic balance and reaction medium properties. The methods of circular dichroism and tryptophan fluorescence were applied to estimate the changes in peptide structure within complexes with bile-salt micelles. Bile salts do not exert a significant influence on the structure of the enzymes under study: in the Rh. miehei and M. javanicus lipases the α-helix content was slightly decreased; an influence of the bile salts on the C. rugosa structure was not revealed. Despite negligible structural modifications in the enzymes, a considerable change in their catalytic properties, namely an abrupt decrease in catalytic effectiveness was observed in bile-salt solutions. Substrate–bile salt micelle complex formation was demonstrated by the NMR self-diffusion method. A model of the regulation of fungal lipase activity was proposed.     

Effect of the interphase surface charge on the structure and activity of trypsin in inverted micelles

The effect of the sign and value of the charge of the interphase surface on the catalytic activity of trypsin in systems of inverted mycelles was investigated. n-Butanol was used for the modification of the phase interface in dispersions of inverted mycelles based on anionic sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and cationic cetyltrimethylammonium bromide (CTAB). A direct correlation between changes in the state of inverted mycelles and the structure of solubilized enzyme under the action of butanol was obtained. It was shown that the enzyme activity is determined by the quantity of butanol solubilized by the inverted mycelles.     

Mechanisms of long-term plasticity of hippocampal GABAergic synapses

Long-term potentiation and depression of synaptic transmission have been considered as cellular mechanisms of memory in studies conducted in recent decades. These studies were predominantly focused on mechanisms underlying plasticity at excitatory synapses. Nevertheless, normal central nervous system functioning requires maintenance of a balance between inhibition and excitation, suggesting existence of similar modulation of glutamatergic and GABAergic synapses. Here we review the involvement of G-protein-coupled receptors in the generation of long-term changes in synaptic transmission of inhibitory synapses. We considered the role of endocannabinoid and glutamate systems, GABA_B and opioid receptors in the induction of long-term potentiation and long-term depression in inhibitory synapses. The preand postsynaptic effects of activation of these receptors are also discussed.     

Association of YWHAE gene polymorphism with suicidal behavior

The importance of YWHAE gene polymorphisms (rs1532976, rs3752826, and rs9393) in the development of suicidal behavior has been studied in ethnic groups of Russians and Tatars from the Republic of Bashkortostan. It was revealed that the carriers of the YWHAE*C allele of rs3752826 polymorphism of the YWHAE gene have increased the risk of suicidal behavior (OR = 1.91), regardless of their ethnicity. In addition, the YWHAE*T allele of rs9393 polymorphism (OR = 2.21), YWHAE*T/*T genotype (OR = 2.73), and YWHAE*T allele (OR = 1.52) of the rs1532976 polymorphism, as well as the YWHAE*A*T haplotype of rs1532976 and rs9393 polymorphisms (OR = 1.54) represent genetic markers of the risk of suicidal behavior in the sample of subjects of Russian ethnicity.     

Resting membrane potential of rat ventroposteriomedial thalamic neurons during postnatal development

Resting membrane potential is a critical parameter determining tonic or bursting mode of the thalamic neurons. Previous studies using whole-cell recordings showed that immature ventroposteriomedial (VPM) and lateral geniculate thalamic neurons are strongly depolarized and have resting membrane potential near ?50 mV. Yet, whole-cell recordings are associated with an introduction of the shunting conductance via the gigaseal that may lead to membrane depolarization in small neurons with high, in the gigaohm range, membrane resistance. Therefore, we have performed measurements of resting potential of VPM neurons in slices obtained from neonatal rats of postnatal days P2-P7 using cell-attached recordings of NMDA channels as voltage sensors. Because currents through the NMDA channels reverse near 0 mV, we assumed that the resting potential should equal the reversal potential of currents through NMDA channels in cell-attached recordings. Analysis of the current-voltage relationships of NMDA currents revealed that the resting potential in the immature VPM neurons is around ?74 mV and that it does not change during the first postnatal week. This suggests that VPM neurons may operate in the bursting mode during the early postnatal period and support the oscillatory activity (spindle-like bursts) in the developing thalamocortical networks.     

Effects of sensitization of the guinea pig slow muscle in disorders of the neurotrophic control]

The immunohistochemical profile of intact and denervated soleus muscle of guinea pigs after sensibilization was studied. It is shown, that intact soleus muscle consists of slow fibers, which have low ATP-ase activity and don't react with monoclonal antibodies against fast myosin heavy chain. No changes of immunohistochemical profile were found after denervation or sensibilization. At the same time, the fibers, reacting with monoclonal antibodies against fast myosin heavy chain and having low ATP-ase activity, were found in denervated muscles after sensibilization. It is concluded, that the synthesis of fast myosin is induced after sensibilization of denervated muscles. Validity of myosin ATP-ase histochemistry for muscle fibers typing is discussed.     

Synthesis and In Vitro Antibacterial Activity of New C-3-Modified Carbapenems

Russian Journal of Bioorganic Chemistry - New C-3 modified carbapenems have been synthesized by the AdNE-substitution of the enol phosphate group of 4-nitrobenzyl...     

Effect of the charge of the interface surface on the structure and activity of trypsin in reversed mycelles

The effect of the sign and value of the charge of the interface surface on the catalytic activity of trypsin in systems of reversed mycelles was investigated. n-Butanol was used for the modification of the phase interface in dispersions of reversed mycelles based on anionic sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and cationic cetyltrimethylammonium bromide (CTAB). A direct correlation between changes in the state of reversed mycelles and the structure of solubilized enzyme under the action of butanol was obtained. It was shown that the enzyme activity is determined by the quantity of butanol solubilized by the reversed mycelles.     

Neurotrophic control of myosin synthesis in guinea pig slow muscle]

After experimental cease of neurotrophic control of skeletal muscle by denervation no changes in myosin ATP-ase histochemistry and immunohistochemical profile in slow (m. soleus) muscle of guinea pig were found. All muscle fibers in intact muscle fibers). However after colchicine blockade of axoplasmic transport in this slow muscle some muscle fibers reacting with monoclonal antibodies against fast myosin heavy chain were found. At the same time no changes in histochemical ATP-ase profile were observed. Validity of myosin ATP-ase histochemistry for muscle fibers typing as well as possible influence of nerve activity and neurotrophic control itself were discussed.