咪达唑仑与人血清白蛋白结合的荧光光谱研究

目的:研究咪达唑仑与人血清白蛋白(HSA)的结合作用。方法:分析咪达唑仑与HSA结合的荧光猝灭光谱和同步荧光光谱(激发波长和发射波长的间距(Δλ)分别为15nm和60nm);由Stern-Volmer方程确定咪达唑仑对HSA17℃和37℃时的荧光猝灭速率常数(Kq)及机制,Lineweaver-Burk双对数方程确定17℃和37℃时猝灭反应结合常数(KA)和结合位点数(n);根据反应前后的焓变ΔH和熵变ΔS的相对大小判断咪达唑仑与HSA之间的主要作用力类型。结果:荧光猝灭光谱显示咪达唑仑与HSA有荧光猝灭作用,Δλ=15nm波长的同步荧光光谱显示咪达唑仑对酪氨酸残基发生作用,未对色氨酸残基发生作用;在17℃和37℃时的Kq分别为5.0246×1011和4.757×1011L·mol-1·s-1;17℃和37℃时猝灭反应KA和n分别为2.1717×104、8.7438×103mol·L-1,1.1895、1.0769个;反应前后的ΔH和ΔS均<0。结论:咪达唑仑对人血清白蛋白的猝灭过程为静态猝灭,咪达唑仑与HSA间的作用力主要为范德华力或者氢键作用力。

Interaction between Midazolam and Human Serum Albumin by Fluorescence Spectrum

OBJECTIVE： To investigate the interaction between midazolam and human serum albumin （HSA）. METHODS： The interaction of midazolam with HSA was studied by measuring fluorescence quenching spectra and synchronous fluorescence spectra （excitation and emission wavelength A2 of 15 nm and 60 nm）. The fluorescence quenching constants （Kq） and mechanism of midazolam to HSA at 17 ℃ and 37 ℃ were determined by Stem-Volmer equation, and the binding constants （KA） and binding sites （n） were calculated according to Lineweaver-Burk equation; the type of binding force was estimated by the calculation of ther- modynamic parameters （enthalpy change AH and entropy change AS） before and after reaction. RESULTS： The fluorescence quen- ching spectra showed that midazolam and HSA had fluorescence＇quenching effect, and synchronous fluorescence spectra of △λ= 15 nm showed that midazolam influenced Tyr residues but Trp residues; the fluorescence quenching spectra showed that Kq were 5.024 6×10^11 and 4.757×10^11 L-mol-1.s-1 at 17 ℃ and 37 ℃; in quenching reaction, KA and n were 2.171 7×10^4 and 8.743 8×10^3 mol.L-1, 1.189 5 and 1.076 9, respectively; AH and AS were both less than zero. CONCLUSION： The fluorescence of HSA quenched by midazolam is static. The interaction between midazolam and HSA is mainly hydrogen bond and van der Waals force.