In this study, production of ct-linoleic acid concentrated from crude perilla oil by gradient cooling urea inclusion was optimized. The fatty acid composition was determined after ethyl esterification by gas chromatog...In this study, production of ct-linoleic acid concentrated from crude perilla oil by gradient cooling urea inclusion was optimized. The fatty acid composition was determined after ethyl esterification by gas chromatography （GC）. In this process, orthogonal experiment was carried out. Under optimum conditions, the maximum amount of α-linoleic acid （91.5%） was obtained at a urea to fatty acid ratio of 3, a solvent to fatty acids ratio of 7, a reaction temperature of 348 K and a crystallization time of 690 min. A simple method of gradient cooling urea inclusion was used to purify α-linolenic acid by using urea to form inclusion complexes with the saturated and the less unsaturated fatty acids, which enhanced the purity of α-linoleic acid ethyl ester by above 90%.展开更多
以费-托合成馏分油为原料,采用梯度冷却尿素络合法对正构烷烃进行分离,生产煤基费-托合成液体石蜡,考察了降温速率和络合反应条件对正构烷烃分离效果的影响,并采用气相色谱-质谱联用仪、详细烃组成分析等方法对产物的组成进行分析,结果...以费-托合成馏分油为原料,采用梯度冷却尿素络合法对正构烷烃进行分离,生产煤基费-托合成液体石蜡,考察了降温速率和络合反应条件对正构烷烃分离效果的影响,并采用气相色谱-质谱联用仪、详细烃组成分析等方法对产物的组成进行分析,结果表明:当反应体系的温度由45℃以1℃min的速率下降至25℃,尿素异丙醇水溶液与油的质量比为10∶1,尿素、异丙醇、水的质量比为38∶40∶22时,经馏分切割得到的重质液体石蜡中正构烷烃质量分数为93%左右,其各项性质满足NB SH T 0416—2014质量标准要求;与传统冷却尿素络合法相比,梯度冷却尿素络合法的液体石蜡产品纯度和正构烷烃回收率均大幅提高。展开更多
Aminoacylase （EC 3. 5. 1. 14） is a dimeric enzyme containing one Zn<sup>2+</sup> ion per subunit with a molecular weight of 43000 u. Zn<sup>2+</sup> ion is located at the active site, and it ...Aminoacylase （EC 3. 5. 1. 14） is a dimeric enzyme containing one Zn<sup>2+</sup> ion per subunit with a molecular weight of 43000 u. Zn<sup>2+</sup> ion is located at the active site, and it is essential for enzyme activity. It is well known that the presence of Zn<sup>2+</sup> ion helps to keep the conformation of the active site in a strained state required for the catalysis of展开更多
Urea gradient gel electrophoresis (UGGE) is an important technique for studying the conformation changes of proteins during denaturation. This paper reports on an investigation of the unfolding and refolding of creati...Urea gradient gel electrophoresis (UGGE) is an important technique for studying the conformation changes of proteins during denaturation. This paper reports on an investigation of the unfolding and refolding of creatine kinase (CK) by UGGE. The native and denatured CK underwent electrophoresis in polyacrylamide gels containing a linear 08 mol/L gradient of urea perpendicular to the direction of migration. The results showed that unfolding and refolding of CK is a relatively rapid process. The denatured enzyme could refold to a conformation with activity during electrophoresis at low urea concentrations, indicating that denaturation in urea is reversible. More importantly, both the native and denatured CK were separated into multiple parallel bands through UGGE, but the bands decreased significantly when mercaptoethanol was added to the samples. The results suggest that various kinds of unfolding and refolding intermediates were formed during UGGE, which are assumed to be oligomers with disulfide bonds between peptide chains. Urea/SDS (sodium dodecylsulphate) polyacrylamide two dimensional electrophoresis proved that these unfolding and refolding intermediates formed during UGGE were oligomers which were composed of different number of subunits cross linked by disulfide bonds. The results indicate that the unfolding and refolding of CK are relatively rapid processes with some cross linked intermediates with disulfide bonds during unfolding and refolding of the enzyme.展开更多
基金the National Natural Science Foundation of China (20871061)the National 973 Program of China (2008CB617512) for the financial support
文摘In this study, production of ct-linoleic acid concentrated from crude perilla oil by gradient cooling urea inclusion was optimized. The fatty acid composition was determined after ethyl esterification by gas chromatography （GC）. In this process, orthogonal experiment was carried out. Under optimum conditions, the maximum amount of α-linoleic acid （91.5%） was obtained at a urea to fatty acid ratio of 3, a solvent to fatty acids ratio of 7, a reaction temperature of 348 K and a crystallization time of 690 min. A simple method of gradient cooling urea inclusion was used to purify α-linolenic acid by using urea to form inclusion complexes with the saturated and the less unsaturated fatty acids, which enhanced the purity of α-linoleic acid ethyl ester by above 90%.
文摘以费-托合成馏分油为原料,采用梯度冷却尿素络合法对正构烷烃进行分离,生产煤基费-托合成液体石蜡,考察了降温速率和络合反应条件对正构烷烃分离效果的影响,并采用气相色谱-质谱联用仪、详细烃组成分析等方法对产物的组成进行分析,结果表明:当反应体系的温度由45℃以1℃min的速率下降至25℃,尿素异丙醇水溶液与油的质量比为10∶1,尿素、异丙醇、水的质量比为38∶40∶22时,经馏分切割得到的重质液体石蜡中正构烷烃质量分数为93%左右,其各项性质满足NB SH T 0416—2014质量标准要求;与传统冷却尿素络合法相比,梯度冷却尿素络合法的液体石蜡产品纯度和正构烷烃回收率均大幅提高。
文摘Aminoacylase （EC 3. 5. 1. 14） is a dimeric enzyme containing one Zn<sup>2+</sup> ion per subunit with a molecular weight of 43000 u. Zn<sup>2+</sup> ion is located at the active site, and it is essential for enzyme activity. It is well known that the presence of Zn<sup>2+</sup> ion helps to keep the conformation of the active site in a strained state required for the catalysis of
文摘Urea gradient gel electrophoresis (UGGE) is an important technique for studying the conformation changes of proteins during denaturation. This paper reports on an investigation of the unfolding and refolding of creatine kinase (CK) by UGGE. The native and denatured CK underwent electrophoresis in polyacrylamide gels containing a linear 08 mol/L gradient of urea perpendicular to the direction of migration. The results showed that unfolding and refolding of CK is a relatively rapid process. The denatured enzyme could refold to a conformation with activity during electrophoresis at low urea concentrations, indicating that denaturation in urea is reversible. More importantly, both the native and denatured CK were separated into multiple parallel bands through UGGE, but the bands decreased significantly when mercaptoethanol was added to the samples. The results suggest that various kinds of unfolding and refolding intermediates were formed during UGGE, which are assumed to be oligomers with disulfide bonds between peptide chains. Urea/SDS (sodium dodecylsulphate) polyacrylamide two dimensional electrophoresis proved that these unfolding and refolding intermediates formed during UGGE were oligomers which were composed of different number of subunits cross linked by disulfide bonds. The results indicate that the unfolding and refolding of CK are relatively rapid processes with some cross linked intermediates with disulfide bonds during unfolding and refolding of the enzyme.
