[Comparison of reabsorption of osmotically free water in the bud and energy of interaction of vasotocin analogs with a V2-receptor].

The calculated values of the binding energy of nonapeptides with receptors in docking with their influence on reabsorption of osmotically free water in a rat bud in vivo were compared. Vasotocin and some its analogs were intramuscularly introduced to non-narcotized rat females of the Wistar line in doses from 0.1 pmol to 0.

Weak toxin WTX from Naja kaouthia cobra venom interacts with both nicotinic and muscarinic acetylcholine receptors.

Iodinated [125I] weak toxin from Naja kaouthia (WTX) cobra venom was injected into mice, and organ-specific binding was monitored. Relatively high levels of [125I]WTX were detected in the adrenal glands. Rat adrenal membranes were therefore used for analysis of [125I]WTX-binding sites.

Steered molecular dynamics simulations of cobra cytotoxin interaction with zwitterionic lipid bilayer: no penetration of loop tips into membranes.

Cobra cytotoxins, small proteins of three-fingered toxin family, unspecifically damage membranes in different cells and artificial vesicles. However, the molecular mechanism of this damage is not yet completely understood. We used steered molecular dynamics simulations to study the interaction of cardiotoxin A3 from Naja atra cobra venom with hydrated 1-palmitoyl-2-oleoyl-1-sn-3-phosphatidylcholine (POPC) bilayer.

[Effects of vasotocin analogs on excretion of Na+, K+, and Mg2+ ions via rat kidney].

Experiments on rats showed that the intramuscular injections of arginine-vasotocin (AVT), 1-deamino-arginine-vasotocin (1dAVT) or 1-deamino-1-monocarba-arginine-vasotocin (1dlmcAVT) at a dose of 5 x 10(-11) mole per 100 g body weight increase renal excretion of Na+, K+, and Mg2+. Antagonist of V1 receptors (OPC-21268) decreases the effect of 1dAVT nonapeptides on renal excretion of the studied ions. A model of VIb-receptor is constructed and a correlation is shown between the energy of interaction of the V1b-receptor and the natriuretic effect of the studied vasotocin analogs.

[Vasopressin receptors: structure and stimulation by 1-deamino-arginine-vasotocin in rats].

In experiments on non-anesthetized female Wistar rats, it has been shown that injection of 1-deamino-arginine-vasotocin (1dAVT) increases sodium excretion and solute-free water reabsorption. Antagonists of V1-receptors (OPC-31260, Otsuka Pharmaceutical Co., Ltd.

Bacterial expression, NMR, and electrophysiology analysis of chimeric short/long-chain alpha-neurotoxins acting on neuronal nicotinic receptors.

Different snake venom neurotoxins block distinct subtypes of nicotinic acetylcholine receptors (nAChR). Short-chain alpha-neurotoxins preferentially inhibit muscle-type nAChRs, whereas long-chain alpha-neurotoxins block both muscle-type and alpha7 homooligomeric neuronal nAChRs. An additional disulfide in the central loop of alpha- and kappa-neurotoxins is essential for their action on the alpha7 and alpha3beta2 nAChRs, respectively.

Behavioural effects in mice and intoxication symptomatology of weak neurotoxin from cobra Naja kaouthia.

Weak neurotoxins belong to the superfamily of three-finger toxins from snake venoms. In general, weak toxins have a low toxicity and, contrary to other three-finger toxins, their molecular targets are not well characterized: in vitro tests indicate that these may be nicotinic acetylcholine receptors. Here, we report the influence of intraperitoneal and intravenous injections of weak neurotoxin from Naja kaouthia venom on mouse behaviour.

A model for short alpha-neurotoxin bound to nicotinic acetylcholine receptor from Torpedo californica.

Short- and long-chain alpha-neurotoxins from snake venoms are potent blockers of nicotinic acetylcholine receptors (nAChRs). Short alpha-neurotoxins consist of 60-62 amino acid residues and include 4 disulfide bridges, whereas long alpha-neurotoxins have 66-75 residues and 5 disulfides. The spatial structure of these toxins is built by three loops, I-III "fingers," confined by four disulfide bridges; the fifth disulfide of long-chain alpha-neurotoxins is situated close to the tip of central loop II.

Acetylcholine-binding proteins: functional and structural homologs of nicotinic acetylcholine receptors.

Acetylcholine-binding protein (AChBP) is a water-soluble protein released from molluscan glial cells and modulates ACh-mediated synaptic transmission. Acetylcholine-binding protein (AChBP) is a water-soluble homolog of the ligand-binding domain of nicotinic receptors and other members of the pharmaceutically important family of pentameric ligand-gated ion channels (LGICs), GABAA, GABAC, 5-HT3 serotonin, and glycine receptors. The crystal structure of AChBP from Lymnaea stagnalis has become an established model for the extracellular domain of the pentameric LGICs, and homology models have been generated to analyze receptor-ligand interactions.

Alpha-conotoxin analogs with additional positive charge show increased selectivity towards Torpedo californica and some neuronal subtypes of nicotinic acetylcholine receptors.

Alpha-conotoxins from Conus snails are indispensable tools for distinguishing various subtypes of nicotinic acetylcholine receptors (nAChRs), and synthesis of alpha-conotoxin analogs may yield novel antagonists of higher potency and selectivity. We incorporated additional positive charges into alpha-conotoxins and analyzed their binding to nAChRs. Introduction of Arg or Lys residues instead of Ser12 in alpha-conotoxins GI and SI, or D12K substitution in alpha-conotoxin SIA increased the affinity for both the high- and low-affinity sites in membrane-bound Torpedo californica nAChR.

Analysis of specificity of antibodies against synthetic fragments of different neuronal nicotinic acetylcholine receptor subunits.

We have compared specificity of a panel of polyclonal antibodies against synthetic fragments of the alpha7 subunit of homooligomeric acetylcholine receptor (AChR) and some subunits of heteromeric AChRs. The antibody interaction with extracellular domain of alpha7 subunit of rat AChR (residues 7-208) produced by heterologous expression in E. coli and rat adrenal membranes was investigated by the ELISA method.

A model for short alpha-neurotoxin bound to nicotinic acetylcholine receptor from Torpedo californica: comparison with long-chain alpha-neurotoxins and alpha-conotoxins.

Short-chain alpha-neurotoxins from snakes are highly selective antagonists of the muscle-type nicotinic acetylcholine receptors (nAChR). Although their spatial structures are known and abundant information on topology of binding to nAChR is obtained by labeling and mutagenesis studies, the accurate structure of the complex is not yet known. Here, we present a model for a short alpha-neurotoxin, neurotoxin II from Naja oxiana (NTII), bound to Torpedo californica nAChR.

Naja melanoleuca cobra venom contains two forms of complement-depleting factor (CVF).

Two forms of complement-depleting cobra venom factor (CVFm1 and CVFm2), possessing molecular masses of 142.6 kDa (CVFm1) and 143.1 kDa (CVFm2), according to MALDI mass-spectrometry, were isolated from the Naja melanoleuca cobra venom.

Crystal structure of nicotinic acetylcholine receptor homolog AChBP in complex with an alpha-conotoxin PnIA variant.

Conotoxins (Ctx) form a large family of peptide toxins from cone snail venoms that act on a broad spectrum of ion channels and receptors. The subgroup alpha-Ctx specifically and selectively binds to subtypes of nicotinic acetylcholine receptors (nAChRs), which are targets for treatment of several neurological disorders. Here we present the structure at a resolution of 2.

Polyclonal antibodies against native weak toxin Naja kaouthia discriminate native weak toxins and some other three-fingered toxins against their denaturated forms.

Polyclonal antibodies obtained by immunization of rabbits with native form of weak toxin (WTX) from cobra Naja kaouthia venom efficiently interacted with WTX and a weak toxin from Naja oxiana venom, but not so with their denaturated forms. These antibodies could also bind with lower affinity other groups of three-fingered toxins: long-chain alpha-neurotoxins, muscarinic toxins and cytotoxins, but practically did not bind short-chain alpha-neurotoxins. The efficiency of toxin-antibody interaction depends on the group (weak toxins, long or short alpha-neurotoxins, cytotoxins etc.

Isothermal reorganization of poly(ethylene terephthalate) revealed by fast calorimetry (1000 K s(-1); 5 ms).

Reorganization of semicrystalline polymers on heating is a fast process. For poly(ethylene terephthalate) (PET) heating rates of several thousand Kelvin per second are needed to prevent reorganization of unstable crystals. Utilizing a thin film vacuum gauge as a fast calorimeter we are able to extend the scanning rate range of commercial DSC's (microK s(-1) to 10 K s(-1)) to rates as high as 10000 K s(-1) on heating and cooling.