Purification and Characterization of a Thermostable Laminarinase from Penicillium rolfsii c3-2(1) IBRL

A laminarinase (endo-β-1,3-glucanase) was purified to homogeneity from Penicillium rolfsii c3-2(1) IBRL, which was originally produced in liquid culture containing 1% xylan from birchwood, via anion-exchange chromatography, gel filtration on Sephacryl S-100, and hydrophobic interaction chromatography. A single protein band with a molecular weight of 75 kDa was detected by sodium dodecyl sulfatepolyacrylamide gel electrophoresis, which had an optimum catalytic activity at pH 4.0 to 5.0 and 70 °C. This purified enzyme was most stable in the pH range 4 to 7, while it was thermostable up to 55 °C and retained up to 90% of its activity after 4 h pre-incubation. A substrate laminarin kinetic study yielded estimated Km and Vmax values of 0.0817 mg/mL and 372.2 μmol/min/mg, respectively. Laminari-oligosaccharide degradation, which was analyzed by thin layer chromatography, yielded the major hydrolysis products laminaribiose and glucose.