RESUMO

Previous studies from our laboratory have demonstrated that the fungus Penicillium frequentans produces high levels of polygalacturonase and pectinesterase. Endopolygalacturonase I (Endo-PG I) and Exopolygalacturonase I (Exo-PG I) were previously purified and characterized. In the present study two extracellular polygalacturonases were separated, partially purified and biochemically characterized. Both were characterized as exopolygalacturonases so they were named exopolygalacturonase II (Exo-PG II) and exopolygalacturonase III (Exo-PG III) which had a molecular mass of 63 kDa (Exo-PG II) and 79 kDa (Exo-PG III). The Km values were 1.6 and 0.059 g/L and the Vmax values were 2571 and 185 U/mg, respectively. The optimum temperature was 50ºC for both enzymes, while the optimum pH was 5.0 for Exo-PG II and 5.8 for Exo-PG III.

Estudos prévios realizados em nosso laboratório demonstraram que o fungo Penicillium frequentans produz altos níveis de poligalacturonase e pectinesterase. Endopoligalacturonase I (Endo-PG I) e Exopoligalacturonase I (Exo-PG I) já foram previamente purificadas e caracterizadas. No presente trabalho foram separadas, purificadas parcialmente e caracterizadas bioquimicamente duas poligalacturonases extracelulares. Ambas foram caracterizadas como exopoligalacturonases e então foram designadas exopoligalacturonase II (Exo-PG II) e exopoligalacturonase III (Exo-PG III) as quais apresentaram massa molecular de 63 kDa (Exo-PG II) e 79 kDa (Exo-PG III). Os valores de Km foram 1,6 e 0,059 g/L e os de Vmáx = 2571 e 185 U/mg, respectivamente. A temperatura ótima de ambas foi 50ºC e enquanto o pH ótimo da Exo-PG II foi 5,0 o da Exo-PG III foi 5,8.