Barrowcliffe T W, Le Shirley Y
National Institute for Biological Standards and Control, Potters Bar, Herts., U.K.
Thromb Haemost. 1989 Nov 24;62(3):950-4.
The anti-Xa activities of unfractionated heparin (UFH) and nine low molecular weight heparins (LMWH) have been measured in the presence and absence of 3 mM CaCl2, using bovine Factor Xa, purified human ATIII and an amidolytic assay. The addition of CaCl2 increased the activity of UFH by 93%, but the effect on LMWH was less, ranging from -20% to +55%. Studies of gel filtration fractions of UFH showed marked Mr dependence of the CaCl2 effect in the range 4,000-12,000. The differences among the various LMW heparins with respect to the effect of CaCl2 were closely correlated with the amount of polysaccharide above an Mr of 6,500. Kinetic studies confirmed the potentiation of the activity of UFH with bovine Xa and showed an even more marked effect using human Xa.
使用牛源X因子a、纯化的人抗凝血酶III（ATIII）并通过酰胺水解测定法，在存在和不存在3 mM氯化钙（CaCl2）的情况下，测定了普通肝素（UFH）和九种低分子量肝素（LMWH）的抗Xa活性。添加CaCl2使UFH的活性提高了93%，但对LMWH的影响较小，范围在-20%至+55%之间。对UFH的凝胶过滤级分的研究表明，在4000 - 12000范围内，CaCl2效应存在明显的分子量（Mr）依赖性。各种LMW肝素在CaCl2效应方面的差异与分子量高于6500的多糖量密切相关。动力学研究证实了UFH与牛源Xa的活性增强，并表明使用人源Xa时效果更明显。
