Purification of heat-stable exo-inulinase from a marine yeast Cryptococcus aureus G7a

• 作 者: JunSheng;ZhenmingChi;FangGong;JingLi;
• 机 构: Ocean University of China,College of Marine Life Science,Yushan Road,No.5,Qingdao,266003,China
• 出 处: 2008全国博士生学术论坛——海洋、水产领域
• 发表日期: 2007年期

　　The extracellular inulinase in the supematant of cell culture of the marine yeast Cryptococcus aureus G7a was purified to homogeneity with a 7.2-fold increase in specific inulinase aetivity as compared to that in the supematant by ultrafiltration,concentration,gel filtration chromatography(SephadexTM G-75)and anion exchange chromatography(DEAE Sepharose Fast Flow Anion Exchange).The molecular weight of the purified enzyme was estimated to be 60.0 kDa.The optimal pH and temperature of the purified enzyme were 5.0 and 50 ℃,respectively.The enzyme was activated by Ca2+,K+,Na+,Fe2+ and Zn2+.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 20.06 mg/ml and 0.0085 mg/min,respectively.A large amount of monosaccharides were detected after the hydrolysis,indicating the purified inulinase had a high exoinulinase activity.