应用FTIR研究超声对牛血清白蛋白二级结构的影响

应用傅里叶变换红外光谱(FTIR)结合荧光光谱研究了牛血清白蛋白(BSA)在超声作用下的结构变化。荧光光谱表明,超声作用使BSA溶液荧光光谱最大发射峰发生了蓝移,表明超声改变了BSA中色氨酸(Trp)残基环境;荧光强度的降低表明超声改变了蛋白质分子的构象,具有荧光猝灭效应。采用对BSA红外光谱酰胺Ⅰ带进行曲线拟合的方法,定量分析了不同超声功率、时间对BSA二级结构的影响,发现超声作用对BSA中的α-螺旋、β-折叠、β-转角及无规卷曲的相对含量有不同程度的影响;超声作用具有使BSA的二级结构由α-螺旋向β-折叠、β-转角转化的趋势,而无规则卷曲含量则基本不受超声影响而保持相对稳定。

Study on the effect of ultrasound on the secondary structure of BSA by FTIR

Structure changes of bovine serum albumin (BSA) under ultrasound treatment were studied using Fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy. The largest emission peak of BSA solution's fluorescence spectra shifted in blue orientation, indicating that the environment of the Trp residues in BSA had altered with ultrasound treatment. The fluorescence intensity of the solution has also decreased with ultrasound, which showed fluorescence quenching effect and the conformation changes of the BSA. The relative contents of a-helix, beta-fold, beta-turn and random coil under different ultrasound treatment power and time were quantitatively determined via analysis of the amide I changes of infrared spectra of BSA using curve fitting method, the secondary structure of BSA had variation trend from alpha-helix to beta-sheet, however, the relative contents random coil had not significant change.