Na^(+)、Ca^(2+)、Cu^(2+)和Zn^(2+)与HSA相互作用的^(23)(Na)-NMR研究

Sodium-23 NMR Studies on Na^+,Ca^(2+), Cu(2+) or Zn^(2+) Binding to Human Serum Aibumin

本文应用~23Na-NMR波谱技术,研究了Na^(+)、Ca^(2+)、Cu^(2+)和Zn^(2+)与人体血清白蛋白(HSA)的相互作用。在实验基础上,通过引入两位快交换模型,拟合计算获得了Na^(+)与HSA相互作用的结合常数和处于结合状态Na^(+)的相关时间;实验表明Ca^(2+)能与Na^(+)竞争同HSA结合,拟合计算获得了两者与HSA相互作用结合常数的比值,棕榈酸钠能增强Ca^(2+)同Na^(+)竞争与HSA结合的能力;从实验上未能观察到Cu^(2+)、Zn^(2+)能同Na^(+)竞争与HSA相互作用的证据。

Pulsed NMR studies of the longitudinal (T1) and transverse (T2) quadru plar relaxation time of 23Na ions have been used to investigate the interaction of Na% Ca2+ , Cu2+ or Zn2+ with human serum albumin (HSA). The relaxation data show that Na+ interact with HSA obviously provided the concentration of HSA is up to 25% (w/w) at 20℃; the binding constant of Na+ is in the order of 108-164 (mol/L) and the correlation time of binding Na+ is about 7.9×10-9(s). Competi-ion between Na+ and Ca2+ for protein binding sites is demonstrated by the effect of Ca2+ on the 23Na relaxation parameters, which provide no evidence of competition between Cu2+ or Zn2 and Na+ for protein binding sitesj the ratio of binding constants between Ca2+ and Na+ is in the order of 0.6-1.1. Addition of palmitoleic sodium to the solution consisting of Na+, Ca2+ and HSA produced marked changes in the 23Na relaxation parameters; they show that the competition between Na+ and Ca2+ for the protein binding sites can be enhanced, ratio of the binding constants up to 3.8-3.9.