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尖吻蝮蛇毒抗凝血因子(ACF)含量和钙离子含量的定量测定及钙离子结合位点的初步研究 总被引:5,自引:0,他引:5
由紫外光谱法测定蛋白质浓度,用ICP测定Ca含量,从而确定一个ACF分子中含一个钙离子.ACF中分子中除一个高亲和性钙结合位点外,至少还有一个低亲和性钙结合位点,只有当过量钙离子存在时,才可能在低亲和性钙结合位点上进一步结合钙离子.Tb3+具有比Ca2+离子更强的键合ACF能力,能定量结合在ACF中的两个位点上,且能全部取代ACF中Ca2+.文中提及的金属离子对ACF的抗凝血活性没有显著的影响. 相似文献
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Extraction and Crystal Structure of β-Sitosterol 总被引:1,自引:0,他引:1
The title compound β-sitosterol(C29H50O), an active phytosterol in many medicinal and edible plants, was characterized by X-ray diffraction analysis and extensive nuclear magnetic resonance(NMR) data. It crystallizes in monoclinic system, space group P21 with C29H50O·1/2H2O, a = 9.4226(7), b = 7.4824(9), c = 36.889(3) , V = 2597.0(4) 3, Z = 4, Dx = 1.084 g/cm3, Mr = 423.70, F(000) = 948, and μ = 0.064 mm-1. The final R = 0.0886 and wR = 0.2234 for 10157 observed reflections(I 2σ(I)). The molecular crystal structure of β-sitosterol shows relative stereochemistry of 24R-ethylcholest-5-en-3β-ol. The molecule is composed of one steroid nucleus(3 six-membered rings and 1 five-membered ring) and one sidechain of 10 carbons. There are two C29H50O molecules and one H2O molecule in a symmetrical unit, and the title compound is stacked into a special laminated structure through hydrogen bonds and van der Waal forces. The special laminated structure was first reported. 相似文献
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The title compound stachyose(C24H42O21),a biologicaly active tetrasaccharide,was characterized by X-ray diffraction analysis.It crystallizes in the orthorhombic system,space group P21212 with C24H42O21,a = 23.8760(3),b = 12.71028(12),c = 10.81279(11) ,V = 3281.36(6) 3,Z = 4,Dc = 1.511 g/cm3,Mr = 746.58,F(000) = 1576,and μ = 1.230 mm-1.The final R = 0.0666 and wR = 0.1797 for 6298 observed reflections(I 2σ(I)).The molecular crystal structure of stachyose shows absolute stereochemistry of β-D-fructofuranosyl α-D-galactopyranosyl-(1→6)-α-D-galactopyranosyl-(1→6)-α-D-glucopyranoside.The molecule is composed of two α-D-galactoses,one α-D-glucose,and one β-D-fructose and sequentially linked as α-Gal(1→6) α-Gal(1→6) α-Glc(1→2) β-Fru.The title compound is stacked into a 3D layer structure through hydrogen bonds.NMR spectra data are also assigned.In the crystal packing,X-ray analysis indicates that there are two intramolecular and eleven intermolecular hydrogen bonds in this compound. 相似文献
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