The interaction of 2-undecanone (2UC) and 2-dodecanone (2DC), two keto-bioactive components from a famous traditional Chinese medicine Houttuynia Cordata Thunb, with bovine serum albumin (BSA) have been investigated below (pH3.78) and above (pH7.40) Isoelectric point (pl) at different temperatures by fluorescent technique and UV-vis spectra. The results clearly show that the bindings of 2UC and 2DC are saturable and have different quenching mechanism below and above pl, but the saturated concentration is quite different. An obvious positive cooperativity was found at 285K and pH7.40 for 2UC and 2DC at low drugs concentration but wasn't at 301 K. The thermodynamic parameters △H0, △G0, △S0 at different temperatures were calculated and showed that hydrophobic interaction force is mainly binding force for 2DC and 2UC. The quenching constant was measured and showed dependence on the acidity, temperature and length of alkyl chain.The effects of some common metal ions and bioactive components from herbal medicine on the binding are also considered. Results also show that under the circumstance of Existence of zinc ion, ANS or Gly.cyrrhetinic acid,addition of 2DU/2UC may cause strong blue shift in the maximum fluorescent wavelength. Evidences show that the interface between sub-domains ⅠA and ⅡA (fatty site 2) is one of binding sites and site Ⅱ may be their another binding site.%运用荧光光谱和紫外光谱,分别在血清蛋白的等电点以下(pH3.78)和以上(pH7.40),研究了鱼腥草的活性成分甲基正壬酮(2UC)和十二酮(2DC)与牛血清蛋白(BSA)的相互作用.结果显示在等电点前后,(2UC)和(2DC)与BSA的结合呈现可饱和模式,但对荧光的猝灭模式不同,而且结合的饱和浓度也不同.285 K和pH7.40下,二者在浓度较低时呈现明显的正协同作用,而在301 K时没有这种现象.计算了不同温度下结合的热力学参数△H0,△G0,△S0,结果显示疏水作用是主要的作用力.猝灭常数显示出酸度、温度和烃链长度的依赖性.考察了常见金属离子和中药活性成分对结合的影响.结果显示当共存锌离子、ANS和甘草次酸时,两种成分的加入会引起最大荧光发射波长的强烈兰移.试验表明脂肪酸2结合位(fatty site 2)是它们的一个结合位点,而药物结合位点Ⅱ(siteⅡ)可能是它们的另一结合位点.
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