1-(1-萘基)-5-苯基-1H-1,2,3-三唑(1-(naphthalen-1-yl)-5-phenyl-1H-1,2,3-triazole,简称NPTA)是一种新合成的三氮唑化合物,研究了其光谱特征及其生物活性.利用PM3半经验方法的Polak-Ribiere共轭梯度法得到了优化的NPTA分子结构,进而用分子对接显示与人血清白蛋白(HSA)的键合模式及位点,再利用紫外光谱、多种荧光光谱法等技术表征了NPTA及其键合HSA的光谱性质.结果表明:共轭多烯π键的存在使得NPTA呈现特征的荧光与紫外光谱.分子模拟的结果表明NPTA可以嵌于HSA分子的疏水腔内,并与精氨酸Arg222形成四个氢键;位点竞争实验确定了NPTA在HSA亚结构域的位点II位发生作用.二维及三维荧光光谱显示NPTA可以猝灭HSA的内源荧光,使其构象发生变化;紫外、同步荧光扫描证实NPTA主要猝灭了HSA色氨酸残基的荧光,并影响了HSA的微环境;较小的各向异性值说明NPTA与HSA结合后生成的配合物弛豫时间较短,结合的较松.荧光滴定法求得不同温度下(299,309和319 K)NPTA与HSA作用的键合常数,键合模式为典型的疏水作用,与分子模拟的结果相一致.另外,测定了NPTA与键合HSA相关的几种物理化学参数.
1-(Naphthalen-l-yl)-5-phenyl-1H-1,2,3-triazole (NPTA), a novel synthesized triazole compound has been char- acterized for its photophysical properties and bioactivity. The structure of NPTA was optimized by semi-empirical PM3 method using the Polak-Ribiere algorithm. Molecular modeling was furtherly performed to reveal the binding mode and site to human serum albumin (HSA). The spectroscopic properties and the binding to HSA of NPTA were investigated by absorp- tion spectra, synchronous fluorescence, 3D fluorescence spectra and fluorescence polarization. The results indicated that the characteristic absorption and fluorescence spectrum could be attributed to the conjugated polyene n bond of NPTA. Molecu- lar docking showed NPTA moiety bound to the hydrophobic cavity of HSA and there are four hydrogen bonds interactions between NPTA and the residues Arg222. Fluorescent displacement measurements confirmed that NPTA bound HSA on site lI. The 2D and 3D fluorescence spectroscopes of NPTA-HSA system indicated that NPTA quenched strongly the intrinsic fluorescence of HSA and induced a conformational change of the protein. The absorption and synchronous fluorescence spectra showed that NPTA could quench the fluorescence of tryptophan mainly and have effect on the microenvironment around HSA in aqueous solution. The low anisotropy values suggested that NPTA molecules were bound in a motionally unrestricted environment introduced by HSA. The binding constants (104 magnitude) and the number of binding sites (n=1) between NPTA and HSA at different temperatures (299, 309 and 319 K) were calculated from relevant fluorescence titration data, which indicated the strong binding between NPTA and HSA. Meanwhile, from the thermodynamic parameter calcula- tion, it could be shown that the acting force was mainly the hydrophobic interactions, which was in good agreement with molecular modeling studies. Under the conditions studied, the values of the negative charge density (δ), the dissociation con- stants