ABSTRACT
The partial characterization and purification of milk clotting enzyme obtained from the (root latex) of Jacaratia corumbensis O. kuntze was studied, by fractional precipitation with ammonium sulphate and ion exchange chromatography. The ammonium sulphate precipitate showed five fractions (AS1- 0-20 percent; AS2 - 20-40 percent; AS3 - 40-60 percent; AS4 - 60-80 percent; AS5 - 80-100 percent) and among the fractions obtained, the 40-60 percent fraction (AS3) showed the highest milk clotting activity with a purification factor of 1.2 fold in relation to the crude extract. This fraction when applied on Mono Q column yielded two protein peaks (p1 and p2), but p1 pool showed the best milk-clotting activity. The optimal pH for the crude and partially purified extract was 6.5 and 7.0, respectively. The maximum milk-clotting activity was at 55ºC for the both crude and partially purified extracts. The enzyme was inhibited by iodoacetic acid which suggested that this enzyme was a cysteine protease, with molecular weight of 33 kDa.
A enzima coagulante de leite obtida de látex de raiz de Jacaratia corumbensis O. kuntze foi caracterizada parcialmente e purificada, por precipitação fracionária com sulfato de amônio e cromatografia de troca de íon. Foram utilizadas cinco frações de sulfato de amônio (AS1 - 0-20 por cento; AS2 - 20-40 por cento; AS3 - 40-60 por cento; AS4 - 60-80 por cento; AS5 - 80-100 por cento), a fração 40-60 por cento (AS3) mostrou alta atividade coagulante com um fator de purificação de 1,2 vezes em relação ao extrato bruto. Esta fração foi aplicada em coluna Mono Q obtendo dois picos de proteína (p1 e p2), o p1 mostrou melhor atividade coagulante. O pH ótimo para o extrato bruto e parcialmente purificado foi 6,5 e 7,0, respectivamente. A atividade coagulante foi atingida a 55ºC para ambos os extratos, bruto e parcialmente purificado. A enzima foi inibida por ácido iodoacético que sugere que esta enzima é uma cisteína protease, com peso molecular de 33 kDa.
ABSTRACT
Clostridium perfringens, a Gram-positive anaerobic bacterium, is widespread in the environment and commonly found in the intestines of animals, including humans. C. perfringens strains are classified into five toxinotypes (A, B, C, D and E) based on the production of four major toxins (alpha, ß, épsilon, iota). However the toxins (theta, delta, lambda and enterotoxin) are also synthesized by C. perfringens strain. Many attempts to purify the toxins produced by C. perfringens have been proposed. In this review we discuss the purification methods used to isolate toxins from C. perfringens reported in last four decades
Subject(s)
Clostridium perfringens , Toxins, Biological , Bacteria, AnaerobicABSTRACT
The partial characterization of extracellular proteases from Streptomyces clavuligerus NRRL 3585 and 644 mutant was investigated. The enzyme production was carried out in batch fermentation using soy bean filtrate as nitrogen source. Maximum activity was obtained after 96h of fermentation with an initial pH of 7.0. The enzyme was partially purified by ammonium sulphate precipitation. Enzymes from the two strains retained 37 per cent of their initial activities at pH 8.0 after 2 h incubation at 25§C. Enzyme half-life at pH 8.0 and 60§C was 40.30 and 53.32 min, respectively for both strains (partially purified extract). The optimum pH was obtained at pH 7.0-8.0 and 8.4 for enzymes produced for 3585 and 644 strains (crude extract), respectively, and 8.4 and 8.0 for enzymes from the partially purified extract 3585 and 644 strains, respectively. The optimum temperature for the crude extract was 21§C for both strains. However, for the partially preparation the optimum temperature was 50§C and 40ºC for S. clavuligerus NRRL 3585 and 644 strains respectively.