The effects of lanthanide ions and their complexes of citrate and DTPA ligandson the fluldity of dipathetoylphosphatidylethanolamine (DPPE) bilayers have been studiedby FT-Raman spectroscopy. The results show that lan...The effects of lanthanide ions and their complexes of citrate and DTPA ligandson the fluldity of dipathetoylphosphatidylethanolamine (DPPE) bilayers have been studiedby FT-Raman spectroscopy. The results show that lanthanide ions oflower concentrationndecrease the nuldity of acyl chains of DPPE bilayers and change the conformation of c C-C backbone from gauche to the trans lanthanide ions of higher concentration, however,increase the fluldity of acyl chains and increase the gauche population of C-C-C backbone.Lanthainde complex of citrate have no effect on the fluidity of acyl chains of DPPE bilayersin the region of experdriental concentration, but La-DTPA complex increase slightly thefluidity of acyl chains. The results also indicated that lanthainde ion of lower concentrationchanged the lattice packing of hydrocarbon chains from hexagonal form to orthorhombicform, but it is still in hexagonal or distorted hexagonal lattice cell in the gel state in thepresence of metaJ ions and lanthanide complexes of higher展开更多
文摘The effects of lanthanide ions and their complexes of citrate and DTPA ligandson the fluldity of dipathetoylphosphatidylethanolamine (DPPE) bilayers have been studiedby FT-Raman spectroscopy. The results show that lanthanide ions oflower concentrationndecrease the nuldity of acyl chains of DPPE bilayers and change the conformation of c C-C backbone from gauche to the trans lanthanide ions of higher concentration, however,increase the fluldity of acyl chains and increase the gauche population of C-C-C backbone.Lanthainde complex of citrate have no effect on the fluidity of acyl chains of DPPE bilayersin the region of experdriental concentration, but La-DTPA complex increase slightly thefluidity of acyl chains. The results also indicated that lanthainde ion of lower concentrationchanged the lattice packing of hydrocarbon chains from hexagonal form to orthorhombicform, but it is still in hexagonal or distorted hexagonal lattice cell in the gel state in thepresence of metaJ ions and lanthanide complexes of higher
文摘对磷脂酶D(phospholipase D,PLD)在有机溶媒-水两相体系中催化磷脂酰胆碱(phosphatidylcholine,PC)和乙醇胺(ethanolamine,EA)合成磷脂酰乙醇胺(phosphatidylethanolamine,PE)的反应条件进行优化,并对反应动力学机制进行了研究。确定最佳反应条件为:温度28℃,p H 5.5,底物摩尔比(EA/PC)20∶1,在此条件下PE产率达87.2%。通过研究底物浓度对反应速率的影响,确定反应符合单底物抑制的Ping-Pang机制。分别以Matlab软件的Fminsearch函数与Lineweaver-Burk双倒数作图法求取动力学参数,结果基本一致,底物乙醇胺EA的抑制常数为Ki B=1.50mmol/L。抑制机理为两分子EA同时结合到一分子磷脂酰基-PLD中间体上,生成磷脂酰基-PLD-(EA)2死端复合物,符合竞争性抑制反应动力学规律。该动力学模型预测与实验数据吻合良好,对PLD催化合成PE反应过程的操作及反应器选型设计具有指导作用。