Mattai J, Kwak J C
Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada.
Biophys Chem. 1988 Sep;31(3):295-9. doi: 10.1016/0301-4622(88)80035-8.
Zn2+ binding to the anticoagulant heparin was examined using a dye spectrophotometric method, with added NaCl concentrations of 0.005, 0.0075, 0.01, 0.02 and 0.04 mol/l. The results are shown as Scatchard plots and demonstrate the entropy-driven anticooperativity of Zn2+ binding to heparin. From these Scatchard plots, intrinsic binding constants are determined and are compared to our earlier data for Mg2+ and Ca2+ binding to heparin at similar ionic strengths (J. Mattai and J.C.T. Kwak, Biochim. Biophys. Acta 677 (1981) 303), and to Manning's two-variable theory (G.S. Manning, Q. Rev. Biophys. 2 (1978) 179) for a generalized system of polyelectrolyte + divalent cations + univalent cations. While Mg2+ binding to heparin is purely electrostatic (delocalized or territorial), Zn2+ and Ca2+ binding is much stronger and more specific. Binding constants for these two cations are identical, suggesting similar mechanisms for Zn2+ and Ca2+ binding to heparin.
采用染料分光光度法研究了在添加氯化钠浓度分别为0.005、0.0075、0.01、0.02和0.04 mol/L的情况下锌离子与抗凝剂肝素的结合情况。结果以Scatchard图表示，证明了锌离子与肝素结合的熵驱动反协同性。从这些Scatchard图中确定了内在结合常数，并将其与我们早期在相似离子强度下镁离子和钙离子与肝素结合的数据（J. Mattai和J.C.T. Kwak，《生物化学与生物物理学报》677 (1981) 303）以及与曼宁的双变量理论（G.S. Manning，《生物物理季评》2 (1978) 179）进行比较，该理论适用于聚电解质 + 二价阳离子 + 单价阳离子的广义体系。虽然镁离子与肝素的结合纯粹是静电作用（离域或局部的），但锌离子和钙离子的结合更强且更具特异性。这两种阳离子的结合常数相同，表明锌离子和钙离子与肝素结合的机制相似。
