Isolation and characterization of paramylon synthase from Euglena gracilis(Euglenophyceae)

The aim of this study was to isolate and characterize the paramylon synthes izing enzyme from Euglena gracilis Klebs. A method for enzyme solubilizatio n with high synthase activity using the zwitterionic detergent 3-[(3-cholam idopropyl)-dimethylammonio]-1-propane sulfonate is presented. Fractionated purification showed that the main enzyme activity was associated with the p aramylon granula fraction, isolated from heterotrophically gown cells of E. gracilis. Further purification by sucrose density centrifugation resulted in a large enzyme complex with an apparent molar mass of 670 kDa (native). The complex remained active throughout the isolation procedures and produce d beta-1,3-glucan in vitro. Two polypeptides of 37 and 54 kDa could be iden tified by photoaffinity labeling with [P-32]-UDP-glucose as substrate after SDS-PAGE.