RESUMO
BACKGROUND AND AIMS: Polyphenol-rich diets have been associated with reduced risk of cardiovascular disease (CVD). However, few prospective epidemiological studies have examined the relationship between classes of ingested polyphenols and risk of CVD. Our aim was to evaluate the association between polyphenol intake and risk of major cardiovascular events in a prospective Spanish cohort. METHODS AND RESULTS: We included 17,065 university graduates (60.7% women, mean age: 37.2 years, age range: 20-89) followed-up for a mean of 10.1 years. Polyphenol intake was assessed at baseline using a validated semi-quantitative 136-item food frequency questionnaire and matching food consumption data with the Phenol-Explorer database. Cox proportional hazards models were used to estimate the adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) for incident cardiovascular events (myocardial infarction, stroke or cardiovascular death). Cherries, chocolate, coffee, apples, and olives were the major sources of variability in polyphenol intake. Participants with higher flavonoids intake (fifth quintile) had a 47% lower incidence of cardiovascular events compared to those in the lowest quintile (HR: 0.53, 95% CI: 0.29-0.98; P for trend = 0.09) after adjusting for potential confounders. The results were non-significant for other polyphenol types. CONCLUSION: The intake of flavonoids showed an inverse association with risk of cardiovascular events in a prospective cohort of Spanish middle-aged adult university graduates. REGISTRATION NUMBER FOR CLINICAL TRIALS: NCT02669602 in Clinical Trials.
Assuntos
Doenças Cardiovasculares/prevenção & controle , Dieta , Polifenóis/administração & dosagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Doenças Cardiovasculares/diagnóstico , Doenças Cardiovasculares/epidemiologia , Inquéritos sobre Dietas , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Polifenóis/classificação , Estudos Prospectivos , Fatores de Proteção , Fatores de Risco , Espanha/epidemiologia , Estudantes , Fatores de Tempo , Universidades , Adulto JovemRESUMO
BACKGROUND: and purpose: The peptide PnPP-19, derived from the spider toxin PnTx2-6 (renamed as δ-CNTX-Pn1c), potentiates erectile function by activating the nitrergic system. Since NO has been studied as an antinociceptive molecule and PnPP-19 is known to induce peripheral antinociception, we intended to evaluate whether PnPP-19 could induce peripheral antinociception through activation of this pathway. EXPERIMENTAL APPROACH: Nociceptive thresholds were measured by paw pressure test. PGE2 (2 µg/paw) was administered intraplantarly together with PnPP-19 and inhibitors/blockers of NOS, guanylyl cyclase and KATP channels. The nitrite concentration was accessed by Griess test. The expression and phosphorylation of eNOS and nNOS were determined by western blot. KEY RESULTS: PnPP-19 (5, 10 and 20 µg/paw) induced peripheral antinociception in rats. Administration of NOS inhibitor (L-NOarg), selective nNOS inhibitor (L-NPA), guanylyl cyclase inhibitor (ODQ) and the blocker of KATP (glibenclamide) partially inhibited the antinociceptive effect of PnPP-19 (10 µg/paw). Tissue nitrite concentration increased after PnPP-19 (10 µg/paw) administration. Expression of eNOS and nNOS remained the same in all tested groups, however the phosphorylation of nNOS Ser852 (inactivation site) increased and phosphorylation of eNOS Ser1177 (activation site) decreased after PGE2 injection. Administration of PnPP-19 reverted this PGE2-induced effect. CONCLUSIONS AND IMPLICATIONS: The peripheral antinociceptive effect induced by PnPP-19 is resulting from activation of NO-cGMP-KATP pathway. Activation of eNOS and nNOS might be required for such effect. Our results suggest PnPP-19 as a new drug candidate to treat pain and reinforce the importance of nNOS and eNOS activation, as well as endogenous NO release, for induction of peripheral antinociception.
Assuntos
Analgésicos/farmacologia , GMP Cíclico/metabolismo , Canais KATP/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Óxido Nítrico Sintase Tipo I/metabolismo , Óxido Nítrico/metabolismo , Peptídeos/farmacologia , Animais , Comportamento Animal/efeitos dos fármacos , Pé/fisiopatologia , Masculino , Óxido Nítrico Sintase Tipo I/análise , Óxido Nítrico Sintase Tipo III/análise , Manejo da Dor , Sistema Nervoso Periférico/efeitos dos fármacos , Fosforilação , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Venenos de AranhaRESUMO
A new fibrinogenolytic metalloproteinase (Bmoo FIBMP-I) was purified from Bothrops moojeni snake venom. This enzyme was isolated through a combination of three chromatographic steps (ion-exchange, molecular exclusion, and affinity chromatography). Analyses by reverse phase chromatography, followed by mass spectrometry, showed the presence of enzyme isoforms with average molecular mass of 22.8 kDa. The SDS-PAGE analyses showed a single chain of 27.6 kDa, in the presence and absence of reducing agent. The protein has a blocked N-terminal. One of the peptides obtained by enzymatic digestion of a reduced and S-alkylated isoform was completely sequenced by mass spectrometry (MS/MS). Bmoo FIBMP-I showed similarity with hemorrhagic factor and several metalloproteinases (MP). This enzyme degraded Aα-chain faster than the Bß-chain and did not affect the γ-chain of bovine fibrinogen. The absence of proteolytic activity after treatment with EDTA, together with the observed molecular mass, led us to suggest that Bmoo FIBMP-I is a member of the P-I class of the snake venom MP family. Bmoo FIBMP-I showed pH-dependent proteolytic activity on azocasein, but was devoid of coagulant, defibrinating, or hemorrhagic activities. The kinetic parameters of proteolytic activity in azocasein were determined (V max = 0.4596 Uh(-1)nmol(-1) ± 0.1031 and K m = 14.59 mg/mL ± 4.610).
RESUMO
Cognitive dysfunction following surgery is a common complication, which increases the incidence of other co-morbid conditions, hospital and health-care costs. The reported rate of the occurrence of post-operative cognitive decline varies with different studies, depending on population profile, type of surgery, definition of cognitive disorder and detection methods, design of study, etc. It remains unclear whether these psychiatric signs and symptoms are direct results of the effects of surgery or general anesthesia. Nonetheless they are more frequent after cardiac surgery and are likely to be multi-factorial, but the patho-mechanisms are not yet fully characterized. This communication provides a synopsis of proteomics tools and delineates novel SELDI-TOF results to evaluate biomarkers in this regard. Presented for the first time is a classification of the clinically relevant forms of post-operative cognitive decline with the advent of a novel subclass.
Assuntos
Líquido Cefalorraquidiano/química , Cognição/fisiologia , Ponte de Artéria Coronária , Análise Serial de Proteínas , Proteoma/análise , Proteômica/métodos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Animais , Humanos , SíndromeRESUMO
A new vasoactive cytolytic toxin, referred to as Sp-CTx, has been purified from the venom of the scorpionfish Scorpaena plumieri by a combination of gel filtration and anion exchange chromatographies. An estimation of Sp-CTx native molecular mass, performed by size exclusion chromatography, demonstrated that it is a 121 kDa protein. Further physicochemical studies revealed its glycoproteic nature and dimeric constitution, comprising subunits of approximately 65 kDa (MALDI-TOF-MS). Such protein has proved to possess a potent hemolytic activity on washed rabbit erythrocytes (EC(50) 0.46 nM), whose effect was strongly reduced after treatment with antivenom raised against stonefish venom -Synanceja trachynis (SFAV). This cross-reactivity has been confirmed by western blotting. Like S. plumieri whole venom (100 microg/mL), Sp-CTx (1-50 nM) caused a biphasic response on phenylephrine pre-contracted rat aortic rings, characterized by an endothelium- and dose-dependent relaxation phase followed by a contractile phase. The vasorelaxant activity has been abolished by l-NAME, demonstrating the involvement of nitric oxide on the response. We report here the first isolation of a cytolytic/vasoactive protein from scorpionfish venom and the data provided suggest structural and functional similarities between Sp-CTx and previously published stonefish hemolytic toxins.
Assuntos
Citotoxinas/química , Venenos de Peixe/química , Peixes Venenosos , Hemolíticos/química , Vasodilatadores/química , Animais , Aorta/efeitos dos fármacos , Citotoxinas/isolamento & purificação , Citotoxinas/toxicidade , Eritrócitos/efeitos dos fármacos , Venenos de Peixe/isolamento & purificação , Venenos de Peixe/toxicidade , Hemolíticos/isolamento & purificação , Hemolíticos/toxicidade , Técnicas In Vitro , Contração Miocárdica/efeitos dos fármacos , Coelhos , Ratos , Vasodilatadores/isolamento & purificação , Vasodilatadores/toxicidadeRESUMO
In the current study, the putative cDNA for PnTx2-6 toxin of the Phoneutria nigriventer spider venom was cloned and expressed as tioredoxin fusion protein in the cytoplasm of Escherichia coli. The fusion protein was purified from the bacterial extracts by combination of immobilized Ni-ion affinity and gel filtration chromatographies. Then, it was cleaved by enterokinase and the generated recombinant PnTx2-6 (rPnTx2-6) was further purified by reverse-phase HPLC. Likewise the native toxin purified from the spider venom, rPnTx2-6 potentiates the erectile function when injected in rats. This result indicates that the production of functional recombinant PnTx2-6 might be an alternative to provide this basic and valuable tool for study, as well as for further understanding such complex physiological system, including its correlation with the central nervous system and local tissue factors.
Assuntos
Ereção Peniana/efeitos dos fármacos , Peptídeos/farmacologia , Venenos de Aranha/farmacologia , Sequência de Aminoácidos , Animais , Cromatografia Líquida de Alta Pressão , Escherichia coli/genética , Injeções Subcutâneas , Masculino , Dados de Sequência Molecular , Peptídeos/administração & dosagem , Peptídeos/isolamento & purificação , Priapismo/induzido quimicamente , Ratos , Proteínas Recombinantes de Fusão/administração & dosagem , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes de Fusão/farmacologia , Venenos de Aranha/administração & dosagem , Venenos de Aranha/isolamento & purificaçãoRESUMO
BACKGROUND AIMS: Stem cells derived from human adipose tissue (ASC) have the capacity for renewal, are easily obtained and have plasticity properties that allow them to differentiate into several cell types, including osteoblast cells. With the aim of understanding the issue of the osteogenic process and finding reliable biomarkers in cells undergoing the osteogeneic differentiation process, this work took advantage of a proteomic approach to identify proteins involved in osteogenesis. METHODS: For this purpose, ASC were analyzed under three conditions: S0, in the absence of stimulation; S1, with 2 weeks of osteogenic medium stimulation; and S2, with 4 weeks of osteogenic medium stimulation. The identification of ASC was carried out by flow cytometry using antibodies specific to known undifferentiated stem cell-surface markers. Cell viability, enzymatic activity, mineral deposition, collagen structure and production and gene analyzes were evaluated for each condition. RESULTS: Phenotypic modifications were observed during the in vitro osteogenic differentiation process by two-dimensional (2-D) differential image gel electrophoresis (DIGE). The proteins were identified by mass espectrometry in tandem (MS/MS) analyzes using Matrix-assisted laser desorption/ionization with TOF/TOF is a tandem mass spectrometry method where two time-of-flight mass spectrometers are used consecutively (MALDI-TOF/TOF). A total of 51 differentially expressed proteins was identified when comparing the three observed conditions. Sixteen different spots were identified in the S0 stage compared with S2, while 28 different spots were found in S2 compared with S0. S1 expressed seven different spots compared with S0 and S2. CONCLUSIONS: These findings suggest the involvement of several proteins directly related to the osteogenic pathway, which can be used to improve understanding of the osteogenic process.
Assuntos
Tecido Adiposo/citologia , Biomarcadores , Células-Tronco Mesenquimais/metabolismo , Osteoblastos/metabolismo , Proteômica , Células Estromais/metabolismo , Tecido Adiposo/cirurgia , Adulto , Biomarcadores/metabolismo , Diferenciação Celular , Separação Celular , Células Cultivadas , Eletroforese em Gel Bidimensional , Feminino , Citometria de Fluxo , Perfilação da Expressão Gênica , Humanos , Células-Tronco Mesenquimais/citologia , Pessoa de Meia-Idade , Osteoblastos/citologia , Proteômica/métodos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Células Estromais/citologiaRESUMO
LyeTx I, an antimicrobial peptide isolated from the venom of Lycosa erythrognatha, known as wolf spider, has been synthesised and its structural profile studied by using the CD and NMR techniques. LyeTx I has shown to be active against bacteria (Escherichia coli and Staphylococcus aureus) and fungi (Candida krusei and Cryptococcus neoformans) and able to alter the permeabilisation of L: -alpha-phosphatidylcholine-liposomes (POPC) in a dose-dependent manner. In POPC containing cholesterol or ergosterol, permeabilisation has either decreased about five times or remained unchanged, respectively. These results, along with the observed low haemolytic activity, indicated that antimicrobial membranes, rather than vertebrate membranes seem to be the preferential targets. However, the complexity of biological membranes compared to liposomes must be taken in account. Besides, other membrane components, such as proteins and even specific lipids, cannot be discarded to be important to the preferential action of the LyeTx I to the tested microorganisms. The secondary structure of LyeTx I shows a small random-coil region at the N-terminus followed by an alpha-helix that reached the amidated C-terminus, which might favour the peptide-membrane interaction. The high activity against bacteria together with the moderate activity against fungi and the low haemolytic activity have indicated LyeTx I as a good prototype for developing new antibiotic peptides.
Assuntos
Antibacterianos/farmacologia , Antifúngicos/farmacologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Venenos de Aranha/química , Animais , Antibacterianos/química , Antibacterianos/isolamento & purificação , Antifúngicos/química , Antifúngicos/isolamento & purificação , Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/isolamento & purificação , Candida/efeitos dos fármacos , Cryptococcus neoformans/efeitos dos fármacos , Relação Dose-Resposta a Droga , Escherichia coli/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Modelos Moleculares , Fosfatidilcolinas/antagonistas & inibidores , Estrutura Secundária de Proteína , Aranhas , Staphylococcus aureus/efeitos dos fármacosRESUMO
Using a proteomic approach, a new structural family of peptides was put in evidence in the venom of the yellow scorpion Tityus serrulatus. Tityus serrulatus Hypotensins (TsHpt) are random-coiled linear peptides and have a similar bradykinin-potentiating peptide (BPP) amino acid signature. TsHpt-I (2.7kDa), the first member of this family, was able to potentiate the hypotensive effects of bradykinin (BK) in normotensive rats. Using the C-terminal of this peptide as a template, a synthetic analog peptide (TsHpt-I([17-25])) was designed to held the BK-potentiating effect. A relevant hypotensive effect, independent on BK, was also observed on both TsHpt (native and synthetic). To better evaluate this hypotensive effect, we examined the vasorelaxation of aortic rings from male Wistar rats and the peptides were able to induce endothelium-dependent vasorelaxation dependent on NO release. Both TsHpt could not inhibit ACE activity. These peptides appear to exert their anti-hypertensive effect through NO-dependent and ACE-independent mechanisms.
Assuntos
Anti-Hipertensivos/química , Anti-Hipertensivos/farmacologia , Venenos de Escorpião/química , Venenos de Escorpião/farmacologia , Vasodilatadores/química , Vasodilatadores/farmacologia , Sequência de Aminoácidos , Animais , Anti-Hipertensivos/isolamento & purificação , Bradicinina/farmacologia , Sinergismo Farmacológico , Masculino , Dados de Sequência Molecular , Óxido Nítrico/metabolismo , Peptídeos/química , Peptídeos/isolamento & purificação , Peptídeos/farmacologia , Peptidil Dipeptidase A/efeitos dos fármacos , Ratos , Ratos Wistar , Venenos de Escorpião/isolamento & purificação , Vasodilatação , Vasodilatadores/isolamento & purificaçãoRESUMO
The venom of the spider Phoneutria nigriventer contains several toxins that have bioactivity in mammals and insects. Accidents involving humans are characterized by various symptoms including penile erection. Here we investigated the action of Tx2-6, a toxin purified from the P. nigriventer spider venom that causes priapism in rats and mice. Erectile function was evaluated through changes in intracavernosal pressure/mean arterial pressure ratio (ICP/MAP) during electrical stimulation of the major pelvic ganglion (MPG) of normotensive and deoxycorticosterone-acetate (DOCA)-salt hypertensive rats. Nitric oxide (NO) release was detected in cavernosum slices with fluorescent dye (DAF-FM) and confocal microscopy. The effect of Tx2-6 was also characterized after intracavernosal injection of a non-selective nitric oxide synthase (NOS) inhibitor, L-NAME. Subcutaneous or intravenous injection of Tx2-6 potentiated the elevation of ICP/MAP induced by ganglionic stimulation. L-NAME inhibited penile erection and treatment with Tx2-6 was unable to reverse this inhibition. Tx2-6 treatment induced a significant increase of NO release in cavernosum tissue. Attenuated erectile function of DOCA-salt hypertensive rats was fully restored after toxin injection. Tx2-6 enhanced erectile function in normotensive and DOCA-salt hypertensive rats, via the NO pathway. Our studies suggest that Tx2-6 could be important for development of new pharmacological agents for treatment of erectile dysfunction.
Assuntos
Neuropeptídeos/farmacologia , Neurotoxinas/farmacologia , Ereção Peniana/efeitos dos fármacos , Pênis/efeitos dos fármacos , Venenos de Aranha/farmacologia , Aranhas , Animais , Modelos Animais de Doenças , Sinergismo Farmacológico , Estimulação Elétrica , Disfunção Erétil/complicações , Disfunção Erétil/tratamento farmacológico , Disfunção Erétil/fisiopatologia , Hipertensão/induzido quimicamente , Hipertensão/complicações , Hipertensão/fisiopatologia , Masculino , NG-Nitroarginina Metil Éster/farmacologia , Neuropeptídeos/isolamento & purificação , Neurotoxinas/isolamento & purificação , Óxido Nítrico/metabolismo , Ereção Peniana/fisiologia , Pênis/inervação , Pênis/metabolismo , Ratos , Ratos WistarRESUMO
Various neurotoxins have been described from the venom of the Brazilian spider Phoneutria nigriventer, but little is known about the venoms of the other species of this genus. In the present work, we describe the purification and some structural and pharmacological features of a new toxin (PRTx3-7) from Phoneutria reidyi that causes flaccid paralysis in mice. The observed molecular mass (4627.26 Da) was in accordance with the calculated mass for the amidated form of the amino acid sequence (4627.08 Da). The presence of an alpha-amidated C-terminus was confirmed by MS/MS analysis of the C-terminal peptide, isolated after enzymatic digestion of the native protein with Glu-C endoproteinase. The purified protein was injected (intracerebro-ventricular) into mice at dose levels of 5 microg/mouse causing immediate agitation and clockwise gyration, followed by the gradual development of general flaccid paralysis. PRTx3-7 at 1 microM inhibited by 20% the KCl-induced increase on [Ca2+]i in rat brain synaptosomes. The HEK cells permanently expressing L, N, P/Q and R HVA Ca2+ channels were also used to better characterize the pharmacological features of PRTx3-7. To our surprise, PRTx3-7 shifted the voltage-dependence for activation towards hyperpolarized membrane potentials for L (-4 mV), P/Q (-8 mV) and R (-5 mV) type Ca2+ currents. In addition, the new toxin also affected the steady state of inactivation of L-, N- and P/Q-type Ca2+ currents.
Assuntos
Canais de Cálcio/efeitos dos fármacos , Ativação do Canal Iônico/efeitos dos fármacos , Venenos de Aranha/farmacologia , Sequência de Aminoácidos , Animais , Canais de Cálcio/genética , Canais de Cálcio/fisiologia , Células Cultivadas , Eletrofisiologia , Feminino , Humanos , Masculino , Camundongos , Dados de Sequência Molecular , Ratos , Ratos Wistar , Homologia de Sequência de Aminoácidos , Venenos de Aranha/química , Venenos de Aranha/isolamento & purificação , Aranhas , Sinaptossomos/efeitos dos fármacos , TransfecçãoRESUMO
The proteomes of the venoms of the Brazilian wandering "armed" spiders Phoneutria nigriventer, Phoneutria reidyi, and Phoneutria keyserlingi, were compared using two-dimensional gel electrophoresis. The venom components were also fractionated using a combination of preparative reverse phase HPLC on Vydac C4, analytical RP-HPLC on Vydac C8 and C18 and cation exchange FPLC on Resource S at pH 6.1 and 4.7, or anion exchange HPLC on Synchropak AX-300 at pH 8.6. The amino acid sequences of the native and S-pyridyl-ethylated proteins and peptides derived from them by enzymatic digestion and chemical cleavages were determined using a Shimadzu PPSQ-21(A) automated protein sequencer, and by MS/MS collision induced dissociations. To date nearly 400 peptides and proteins (1.2-27 kDa) have been isolated in a pure state and, of these, more than 100 have had their complete or partial amino acid sequences determined. These sequences demonstrate, as might be expected, that the venoms of P. reidyi and P. keyserlingi (Family: Ctenidae) both contain a similar range of isoforms of the neurotoxins as those previously isolated from P. nigriventer which are active on neuronal ion (Ca(2+), Na(+) and K(+)) channels and NMDA-type glutamate receptors. In addition two new families of small (3-4 kDa) toxins, some larger protein (>10 kDa) components, and two serine proteinases of the venom of P. nigriventer are described. These enzymes may be responsible for some of the post-translational modification observed in some of the venom components.
Assuntos
Neurotoxinas/química , Venenos de Aranha/química , Aranhas , Sequência de Aminoácidos , Animais , Brasil , Feminino , Moscas Domésticas/efeitos dos fármacos , Dose Letal Mediana , Masculino , Camundongos , Dados de Sequência Molecular , Neurotoxinas/isolamento & purificação , Neurotoxinas/toxicidade , Peptídeos/química , Peptídeos/isolamento & purificação , Peptídeos/toxicidade , Proteínas/química , Proteínas/isolamento & purificação , Proteínas/toxicidade , Proteoma , Alinhamento de Sequência , Venenos de Aranha/isolamento & purificação , Venenos de Aranha/toxicidadeRESUMO
AIMS: The aim of this work was to purify and characterize antibacterial compounds produced by Lactobacillus murinus strain L1. METHODS AND RESULTS: Antagonistic activity was observed in a deferred agar-spot assay against spoilage and pathogenic bacteria, but not against lactobacilli. The inhibitory activity occurred between pH 3.0 and 5.0, and was heat stable. The active compounds were purified by gel filtration chromatography and two peaks of antibacterial activity were observed using Bacillus cereus ATCC 11778 and Shigella sonnei ATCC 11060 as indicator strains. Two active low molecular weight compounds were responsible for this phenomenon and UV spectroscopy, gas chromatography and mass spectrometry were used to characterize them. One of them is lactic acid, while the other is a mono-substituted aromatic ring apparently constituted by group residues of m/z 192 linked in tandem to phenylalanine. CONCLUSIONS: Lactobacillus murinus produces at least two low molecular weight compounds active against B. cereus and Sh. sonnei. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first purification of a new broad-spectrum antibacterial compound from Lact. murinus which inhibits various pathogenic and food spoilage bacteria without acting on other lactobacilli. Using it as a biotechnological control agent of bacterial spoilage may be a promising possibility for the food industry.
Assuntos
Antibacterianos/isolamento & purificação , Lactobacillus/metabolismo , Animais , Bacillus cereus/efeitos dos fármacos , Cromatografia Gasosa/métodos , Cromatografia em Gel/métodos , Meios de Cultura , Fezes/microbiologia , Concentração de Íons de Hidrogênio , Espectrometria de Massas/métodos , Peso Molecular , Peptídeo Hidrolases/metabolismo , Ratos , Ratos Wistar , Shigella sonnei/efeitos dos fármacos , Espectrofotometria Ultravioleta/métodos , TemperaturaRESUMO
Enzymes with gelatinolytic activity were detected in Tityus bahiensis and Tityus serrulatus venom. Their activity was optimal at pH 8.0 in SDS-PAGE-gelatin. They were inhibited by PMSF but not by iodoacetamide, pepstatin or phenantrolin in the assay conditions used. This suggests that these enzymes are serine proteases. The presence of metal ions did not affect the proteolytic activity of these enzymes. Several possible functions may be envisaged for these enzymes: in tissue permeabilization, pancreatitis and toxin processing.
Assuntos
Gelatinases/metabolismo , Venenos de Escorpião/enzimologia , Escorpiões/fisiologia , Animais , Eletroforese em Gel de Poliacrilamida , Gelatinases/análise , Fluoreto de Fenilmetilsulfonil/metabolismo , Inibidores de Proteases/metabolismo , Venenos de Escorpião/químicaRESUMO
We report here the isolation by a two-step chromatographic procedure of two new toxins from the South American scorpion Tityus bahiensis. Their amino-acid sequences and some of their biological features were established. The two toxins have different biological properties. Toxin TbIT-I had almost no activity or pharmacological effects in vertebrate tissues whereas it was lethal to house flies (LD50 80.0 ng/house fly). In contrast, Tb2-II was active against both mammals (intracerebroventricular injection of 100 ng/mouse was lethal) and insects (LD50 40.0 ng/house fly). The amino-acid sequences of these toxins were established and found to be similar (60-95%) to previously described beta-toxins from the Tityus genus. Based on the available comparative information, this study attempts identify possible structure-function relationships that may be responsible for the differences in bioactivity displayed by these toxins.