以同步荧光法研究了298, 310, 318 K下硝苯地平(NDP)与胃蛋白酶(PEP)的荧光基团酪氨酸残基(P-Tyr)、色氨酸残基(P-Trp)之间的相互作用。表明药物以动态猝灭的方式猝灭P-Tyr、P-Trp的荧光, 结合位点数n为1, 主要作用力是疏水作用。310 K时NDP与PEP氨基酸残基反应的荧光猝灭比率份数P-Trp 53.43%>P-Tyr 46.57%, 结合位置更靠近P-Trp, NDP与蛋白结合率P-Tyr: 69.43%~87.15%, P-Trp: 73.64%~90.60%, 分别建立了结合模型。且Hill系数nH约为1, 该结合与后继配体无协同作用。结合距离r都小于7 nm, 则NDP与P-Tyr、P-Trp之间都存在非辐射能量转移。

The interactions between fluorophore tyrosine residues(P-Tyr) and tryptophan residues (P-Tyr) of pepsin(PEP) and nifedipine(NDP) at 298, 310 and 318 K were studied by synchronous fluorescence spectroscopy. The results showed that the drug quenches the fluorescence of P-Tyr and P-Trp by means of dynamic quenching. The number of binding sites was 1, and the main force was hydrophobicity. The fluorescence quenching ratio of NDP to PEP amino acid residues at 310 K was P-Trp 53.43%>P-Tyr 46.57%, meaning the binding site was closer to P-Trp. The binding rates of NDP to protein were P-Tyr: 69.43%-87.15% and P-Trp: 73.64%-90.60%, established a binding model, respectively. The Hill coefficient nH was about 1, meaning this combination has no synergistic effect with subsequent ligand. The binding distance r was less than 7 nm in both cases. Thus, non-radiative energy transfer exists between NDP and P-Tyr as well as between NDP and P-Trp.