RESUMO
Aspartic proteinases in the gastric fluid of clawed lobsters Homarus americanus and Homarus gammarus were isolated to homogeneity by single-step pepstatin-A affinity chromatography; such enzymes have been previously identified as cathepsin D-like enzymes based on their deduced amino acid sequence. Here, we describe their biochemical characteristics; the properties of the lobster enzymes were compared with those of its homolog, bovine cathepsin D, and found to be unique in a number of ways. The lobster enzymes demonstrated hydrolytic activity against synthetic and natural substrates at a wider range of pH; they were more temperature-sensitive, showed no changes in the K(M) value at 4°C, 10°C, and 25°C, and had 20-fold higher k(cat)/K(M) values than bovine enzyme. The bovine enzyme was temperature-dependent. We propose that both properties arose from an increase in molecular flexibility required to compensate for the reduction of reaction rates at low habitat temperatures. This is supported by the fast denaturation rates induced by temperature.
Assuntos
Aclimatação/fisiologia , Ácido Aspártico Proteases/metabolismo , Temperatura Baixa , Ácido Gástrico/enzimologia , Nephropidae/enzimologia , Animais , Ácido Aspártico Proteases/fisiologia , Catepsina D/metabolismo , Bovinos , Cromatografia de Afinidade , Concentração de Íons de Hidrogênio , Nephropidae/fisiologia , Pepstatinas , Especificidade da EspécieRESUMO
Las enzimas pancreáticas constituyen agentes terapéuticos de utilidad clínica dentro de un espectro mucho más amplio del que se acepta habitualmente. En este trabajo se trata de demostrar que ejercen una influencia benéfica en un variado grupo de entidades... y que la asociación de una mejora en el mecanismo del proceso digestivo, especialmente de los carbohidratos, y el consecutivo alivio de los fenómenos dispépticos fermentativos, ello en conjunción con una atenuación de la hipersensibilidad del sistema nervioso aferente, cambio muy ligado a una depresión liberadora sobre la CCK, explican el valor terapéutico innegable que poseen los fermentos pancreáticos en el enfoque terapéutico del colon irritable
Assuntos
Adulto , Humanos , Cães , Ácido Gástrico/enzimologia , Ácido Gástrico , Doenças Funcionais do Colo , Enzimas , PâncreasRESUMO
Las enzimas pancreáticas constituyen agentes terapéuticos de utilidad clínica dentro de un espectro mucho más amplio del que se acepta habitualmente. En este trabajo se trata de demostrar que ejercen una influencia benéfica en un variado grupo de entidades... y que la asociación de una mejora en el mecanismo del proceso digestivo, especialmente de los carbohidratos, y el consecutivo alivio de los fenómenos dispépticos fermentativos, ello en conjunción con una atenuación de la hipersensibilidad del sistema nervioso aferente, cambio muy ligado a una depresión liberadora sobre la CCK, explican el valor terapéutico innegable que poseen los fermentos pancreáticos en el enfoque terapéutico del colon irritable
Assuntos
Adulto , Humanos , Cães , Pâncreas/metabolismo , Doenças Funcionais do Colo/enzimologia , Ácido Gástrico/enzimologia , Ácido Gástrico/metabolismo , EnzimasRESUMO
Coleus barbatus (Labiatae) Benth is popularly used in Brazil "for the healing of liver and stomach diseases". The water extract (WE 1 to 10 g/Kg, p.o.) of stem and leaves given to rats and mice did not induce signs of intoxication. Preveious treatment of mice with WE (1 g/kg, p.o.) shortened the sleeping time induced by pentobarbital (50 mg/Kg, i.p.) by 37 por cento, althoyugh the extract alone did not increase the spontaneous activity nor did it induce hyperexcitability. In mice WE (2 g/Kg, p.o.) increased the intestinal transit of charcoal by 30 por cento, while reduced gastric secretions ion rats treated with WE (2g/Kg intraduodenal) 3,9 ± 1.0 to 0.5 ± 0.2 ml/4h, respectively). The treatment also reduced the total acid secretion from 34.4 ± 11.0 to 2.7 ± 0.5 mEq/l and raisedgastric pH from 2.2 ± 0.3 to 6.5 ± 0.8. Treatment with WE (2g/Kg, p.o.) protected against gastric ulcers induced by stress (5.3 ± 1.6 and 1.5 ± 0.5 ulcers/cm²), but did nor protect against indonethacin induced ulcers. The results show that the water extract of C barbatus Benth produces mild stimulation of thecentral nervous system and increases intestinal movements. The extract also reduces gastric secretion indicating an antidyspeptic activity, and protects against gastric ulcers induced by stress.