文摘
Extracellular pectin lyase (PL) (EC 4.2.2.10) was produced by Geobacillus stearothermophilus Ah22 in solid state fermentation. The PL enzyme was purified 40.8-fold by DEAE-cellulose anion exchange column chromatography and characterized. The molecular weight of the enzyme was determined as 36?kDa by Sephadex G-100 gel filtration chromatography. Purification of the enzyme was verified by SDS-PAGE. The optimum pH and temperature of the enzyme were determined as pH?6.0 and 60°C, respectively. The PL was mostly stable at 40°C. Its activity deceased by 50% after 2?h at 60°C and by 60% after 6?h at 50°C. The V max and K m were calculated as 0.47?mg/mL and 355.3?μmol/L·min, respectively. The presence of 10?mM Ca2+, Cu2+, Mn2+, Mg2+, Zn2+, Hg2+, Fe2+ and EDTA, l-cysteine and ascorbic acid significantly enhanced enzyme activity. The purified PL enzyme was used in the production of fruit juices; yields of fruits juice improved significantly compared with controls.