Grant D, Long W F, Moffat C F, Williamson F B
Department of Molecular and Cell Biology, University of Aberdeen, Marischal College, Scotland, U.K.
Biochem J. 1992 Mar 1;282 ( Pt 2)(Pt 2):601-4. doi: 10.1042/bj2820601.
Possible inflexions in isothermal binding plots derived from equilibrium-dialysis measurements and in equivalent plots obtained by polarimetric measurements accord with the possibility that discrete Ca(2+)-heparin-water complexes/phases may exist, the nature and proportions of which depend on the conditions under which the interaction occurs. Analysis of the plots obtained by polarimetric study of chemically modified heparins suggests, for individual substituents groups, an order of importance of carboxylate greater than N-sulphonate greater than N-acetyl greater than O-sulphate for the Ca(2+)-heparin interaction occurring at [Ca2+]/[heparin disaccharide] ratios of less than 0.5. At higher ratios, transitions occur that eventually lead to the formation of a complex in which the stoichiometry of association is 1 Ca2+ ion/heparin disaccharide unit.
由平衡透析测量得到的等温结合曲线以及通过旋光测量获得的等效曲线中可能出现的拐点，符合离散的Ca(2+)-肝素-水复合物/相可能存在的情况，其性质和比例取决于相互作用发生的条件。对化学修饰肝素进行旋光研究得到的曲线分析表明，对于单个取代基团，在[Ca2+]/[肝素二糖]比值小于0.5时发生的Ca(2+)-肝素相互作用中，羧酸根的重要性顺序大于N-磺酸根大于N-乙酰基大于O-硫酸根。在更高的比值下，会发生转变，最终导致形成一种结合化学计量为1个Ca2+离子/肝素二糖单位的复合物。
