对来自新疆天山冻土的Rahnella sp．R3所产的胞内低温β-半乳糖苷酶进行纯化，并对其酶学性质进行研究。采用硫酸铵分级沉淀、Phenyl Sepharose CL-4B疏水层析、QSepharose High Performance阴离子交换层析、Sephacryl S-200 High Resol...对来自新疆天山冻土的Rahnella sp．R3所产的胞内低温β-半乳糖苷酶进行纯化，并对其酶学性质进行研究。采用硫酸铵分级沉淀、Phenyl Sepharose CL-4B疏水层析、QSepharose High Performance阴离子交换层析、Sephacryl S-200 High Resolution凝胶过滤层析，得到电泳纯酶。酶的活性回收率为21．3％，纯化倍数为35．6，比酶活由1．28U／mg提高到45．54U／mg。SDS—PAGE电泳显示其表观分子量为57．3kDa。酶学性质研究表明，该酶最适反应温度为45℃，在15℃时的酶活为最高酶活的40％，4℃时的酶活为最高酶活的23％。该酶对热敏感，45℃保温45min酶活全部丧失。纯酶的最适PH为7．0，在pH6．5～7．5时保持稳定。5mmol／LNa^＋、Ca^2＋、Cu^2＋、Al^3＋、Zn^2＋对酶活力有不同程度的抑制作用，其中Al^3＋抑制K^＋作用最强，Na^＋、Ca^2＋抑制作用不明显。5mmol／LMg^2＋、K^＋对酶活力具有促进作用，其中Mg^2＋促进作用较强，使酶活提高到1．19倍。25℃以ONPG为底物的Vmax，Km值分别为7．19mol／（min·mL）、4．64mmol／L。展开更多
Steel catenary riser（SCR） is the transmission device between the seabed and the floating production facilities. As developments move into deeper water, the fatigue life of the riser can become critical to the whole ...Steel catenary riser（SCR） is the transmission device between the seabed and the floating production facilities. As developments move into deeper water, the fatigue life of the riser can become critical to the whole production system, especially due to the vortex-induced vibration（VIV）, which is the key factor to operational longevity. As a result, experimental investigation about VIV of the riser was performed in a large plane pool which is 60 m long, 36 m wide and 6.5 m deep. Experiments were developed to study the influence of current speed and seabed on VIV of SCR. The results show that amplitudes of strain and response frequencies increase with the current speed both in cross-flow（CF） and in-line（IL）. When the current speed is high, multi-mode response is observed in the VIV motion. The amplitudes of strain in IL direction are not much smaller than those in CF direction. The seabed has influence on the response frequencies of riser and the positions of damage for riser.展开更多
文摘对来自新疆天山冻土的Rahnella sp．R3所产的胞内低温β-半乳糖苷酶进行纯化，并对其酶学性质进行研究。采用硫酸铵分级沉淀、Phenyl Sepharose CL-4B疏水层析、QSepharose High Performance阴离子交换层析、Sephacryl S-200 High Resolution凝胶过滤层析，得到电泳纯酶。酶的活性回收率为21．3％，纯化倍数为35．6，比酶活由1．28U／mg提高到45．54U／mg。SDS—PAGE电泳显示其表观分子量为57．3kDa。酶学性质研究表明，该酶最适反应温度为45℃，在15℃时的酶活为最高酶活的40％，4℃时的酶活为最高酶活的23％。该酶对热敏感，45℃保温45min酶活全部丧失。纯酶的最适PH为7．0，在pH6．5～7．5时保持稳定。5mmol／LNa^＋、Ca^2＋、Cu^2＋、Al^3＋、Zn^2＋对酶活力有不同程度的抑制作用，其中Al^3＋抑制K^＋作用最强，Na^＋、Ca^2＋抑制作用不明显。5mmol／LMg^2＋、K^＋对酶活力具有促进作用，其中Mg^2＋促进作用较强，使酶活提高到1．19倍。25℃以ONPG为底物的Vmax，Km值分别为7．19mol／（min·mL）、4．64mmol／L。
基金financially supported by the National High Technology Research and Development Program of China(863 Program,Grant No.2010AA09Z303)the National Natural Science Foundation of China(Grant No.41174157)Shandong Province Scientific Research Foundation for Outstanding Young Scientists Program(Grant No.BS2013HZ014)
文摘Steel catenary riser（SCR） is the transmission device between the seabed and the floating production facilities. As developments move into deeper water, the fatigue life of the riser can become critical to the whole production system, especially due to the vortex-induced vibration（VIV）, which is the key factor to operational longevity. As a result, experimental investigation about VIV of the riser was performed in a large plane pool which is 60 m long, 36 m wide and 6.5 m deep. Experiments were developed to study the influence of current speed and seabed on VIV of SCR. The results show that amplitudes of strain and response frequencies increase with the current speed both in cross-flow（CF） and in-line（IL）. When the current speed is high, multi-mode response is observed in the VIV motion. The amplitudes of strain in IL direction are not much smaller than those in CF direction. The seabed has influence on the response frequencies of riser and the positions of damage for riser.
