Characterization of a new muscarinic toxin from the venom of the Brazilian coral snake Micrurus lemniscatus in rat hippocampus

AbstractAimsWe have isolated a new muscarinic protein (MT-Mlα) from the venom of the Brazilian coral snake Micrurus lemniscatus.Main methodsThis small protein, which had a molecular mass of 7,048Da, shared high sequence homology with three-finger proteins that act on cholinergic receptors. The first 12 amino acid residues of the N-terminal sequence were determined to be: Leu-Ile-Cys-Phe-Ile-Cys-Phe-Ser-Pro-Thr-Ala-His.Key findingsThe MT-Mlα was able to displace the [3H]QNB binding in the hippocampus of rats. The binding curve in competition experiments with MT-Mlα was indicative of two types of [3H]QNB-binding site with pKi values of 9.08±0.67 and 6.17±0.19, n=4, suggesting that various muscarinic acetylcholine receptor (mAChR) subtypes may be the target proteins of MT-Mlα. The MT-Mlα and the M1 antagonist pirenzepine caused a dose-dependent block on total [3H]inositol phosphate accumulation induced by carbachol. The IC50 values for MT-Mlα and pirenzepine were, respectively, 33.1 and 2.26 nM. Taken together, these studies indicate that the MT-Mlα has antagonist effect on mAChRs in rat hippocampus.SignificanceThe results of the present study show, for the first time, that mAChRs function is drastically affected by MT-Mlα since it not only has affinity for mAChRs but also has the ability to inhibit mAChRs

Segregação e Acondicionamento de Produtos Químicos: Implantação de um Sistema Seguro na Área de Química de Proteínas do Laboratório de Bioquímica e Biofísica – Instituto Butantan

Increasingly the production of chemical products has been made necessary and consequently there is a rise in the exposition to these materials and to its correlate effects, like operational risks, to the health and to the environment. In this way the segregation and storage programs of chemical products is extremely important. In face of this fact the Protein Chemistry Facility has established a safe handling and storage system for chemical products with the purchase/improvement of individual and collective protection equipment, making abridged safety records, structuring a proper area for keeping chemical products regarding compatibility and capacitation of related personnel. All these actions aim at the safety and well-being of all people on the area, plus minimization of environmental risks. DOI: http://dx.doi.org/10.17807/orbital.v8i3.87

Lonomia obliqua venom action on fibrinolytic system

Accidental skin contact with the Lonomia caterpillar bristles causes a severe hemorrhagic syndrome. While fibrinolytic activation is considered to be the main cause of hemorrhage in Lonomia achelous envenomation, a consumptive coagulopathy was found to be a major component involved in the bleeding complications observed in patients envenomed by contact with Lonomia obliqua. Although we have previously observed that in L. obliqua envenomations, fibrinolysis activation appeared to be secondary to coagulation system activation, there are no reports regarding the ability of L. obliqua venom to activate directly fibrinolytic pathways. We examined the action of L. obliqua crude bristles extract (LOCBE) on several fibrinolytic system components. We demonstrated that LOCBE degraded the A-alpha fibrinogen chain only at high concentrations and after long incubation times. Under these conditions, LOCBE also induced prolongation of the fibrinogen clotting time, but no clot lysis was observed before 24 h. LOCBE did not contain t-PA- or u-PA-like activities. Gel filtration and SDS-PAGE showed that LOCBE did not induce FXIII digestion. In addition, no FXIII activity inhibition was detected by dansylcadaverin method. FXIII levels remained unchanged when FXIII was measured in fibrinogen-depleted LOCBE-treated rat plasma, suggesting that the observed 50% FXIII reduction in rats was related to consumption. In conclusion, our results clearly demonstrated that LOCBE did not display either FXIII inhibition or degradation nor fibrinolytic activity. Furthermore, although proteolytic activity on Aα fibrinogen chain was observed, cross-linked fibrin was not affected by LOCBE. © 2003 Elsevier Ltd. All rights reserved.Fil: Fritzen, Márcio. Governo do Estado de Sao Paulo. Secretaria da Saude. Instituto Butantan; BrasilFil: Schattner, Mirta Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Quintana Ribeiro, Ana Laura. Governo do Estado de Sao Paulo. Secretaria da Saude. Instituto Butantan; BrasilFil: Correia Batista, Isabel De Fátima. Governo do Estado de Sao Paulo. Secretaria da Saude. Instituto Butantan; BrasilFil: Ventura, Janaina. Governo do Estado de Sao Paulo. Secretaria da Saude. Instituto Butantan; BrasilFil: Carlos Prezoto, Benedito. Governo do Estado de Sao Paulo. Secretaria da Saude. Instituto Butantan; BrasilFil: Chudzinski-Tavassi, Ana Marisa. Governo do Estado de Sao Paulo. Secretaria da Saude. Instituto Butantan; Brasi

Binding of longipin to lipid membranes.

<p>(<b>A</b>) Filtration binding assay of longipin binding to LUVs composed of POPC or POPG. The peptide was detected in the filtrate by monitoring the fluorescence of Tyr residues (λ_EX = 275 nm / λ_EM = 302 nm). (<b>B</b>) Titration of 20 μM longipin with LUVs composed of POPG, POPC and POPG:POPC (1:1 molar ratio). (<b>C</b>) Titrations at different NaCl concentrations in the 20 μM longipin solution with POPG:POPC LUVs. Dissociation constants (<i>Kd</i>) were determined for each condition.</p

Sequence similarities between longipin and heme-lipoproteins from the ticks <i>Amblyomma americanum</i> (GenBank: ABK40086.2) and <i>Dermacentor variabilis</i> (GenBank: ABD83654.1).

<p>Sequence similarities between longipin and heme-lipoproteins from the ticks <i>Amblyomma americanum</i> (GenBank: ABK40086.2) and <i>Dermacentor variabilis</i> (GenBank: ABD83654.1).</p

Dye leakage induced by longipin.

<p>Dye leakage assay from CF-loaded POPG:POPC vesicles in 80 mM NaCl. Longipin (traced line), melittin (dotted line) or buffer (continuous line) were added at ~ 200 s to a final concentration of 20 μM. CF fluorescence was monitored (λ_EX = 474 nm / λ_EM = 518 nm), and Triton X-100 was added to a final 0.1% concentration to achieve the maximum fluorescence intensity.</p