论文部分内容阅读
The extracellular inulinase in the supernatant of cell culture of the marine yeast Pichia guilliermondii 1 was purified to homogeneity with a 7.2-fold increase in inulinase activity as compared to that in the supernatant by ultrafiltrafion,concentration,gel filtration chromatography(SephadexTM G-75)and anion-exchange chromatography(DEAE-Sepharose Fast Flow Anion-Exchange).The molecular mass of the purified enzyme was estimated to be 50.0 kDa.The optimal pH and temperature of the purified enzyme were 6.0 and 60 ℃,respectively.The enzyme was activated by Mn2+,Ca2+,K+,Li+,Na+,Fe3+,Fe2+,Cu2+,and Co2+.However,Mg2+,Hg2+ and Ag+ acted as inhibitors in decreasing activity of the purified inulinase.The enzyme was strongly inhibited by Phenylmethanesulphonyl fluoride(PMSF),iodoacetic acid,EDTA,and 1,10-phenanthroline.The Km and Vmax values of the purified enzyme for inulin were 21.1 mg ml-1 and 0.082 mg min-1,respectively.A large amount of monosaccharides were detected after the hydrolysis of inulin.