高强度聚焦超声对溶菌酶结构的影响

Effects of high intensity focused ultrasound on lysozyme structure

摘要:

目的：探讨高强度聚焦超声（high intensity focused ultrasound，HIFU）对一种蛋白质—溶菌酶结构的影响。方法：使用频率0.94 MHz、声强3.25×104 W/cm2、脉冲重复频率4 Hz、占空比10%的脉冲高强度聚焦超声辐照溶菌酶溶液10 s。利用圆二色光谱（CD光谱）、荧光光谱、核磁共振氢谱（1H nuclear magnetic resonance，1H-NMR）和聚丙烯酰胺凝胶电泳（sodium dodecyl sulfate-polyacrylamide gel，SDS-PAGE）方法，分别研究高强度聚焦超声对溶菌酶二级、三级和四级结构的影响。结果：高强度聚焦超声处理后，CD光谱无明显变化，表明高强度聚焦超声对溶菌酶二级结构影响不大；而荧光强度减弱，说明溶菌酶色氨酸周围的疏水结构发生了变化；SDS-PAGE结果显示，经高强度聚焦超声辐照后溶菌酶出现支链降解；分析 1H-NMR发现，辐照后溶菌酶色氨酸发生了化学位移。结论：高强度聚焦超声可以改变溶菌酶的高级结构。

Abstract:

Objective：To investigate the effect of high intensity focused ultrasound（HIFU） on the lysozyme molecular structure. Meth－ods：The lysozyme solution was exposed at HIFU with pulse frequency of 0.94 MHz，sound intensity of ３.25×104 W/cm2，pulse repetition period of 4 Hz and duty cycle of 10% for 10 s. The effect of HIFU on the lysozyme molecular structure was studied using CD spectra，fluorescence spectrum，1H nuclear magnetic resonance（1H-NMR） and sodium dodecyl sulfate-polyacrylamide gel（SDS-PAGE） method. Results：The Result showed that after HIFU treatment，there was no obvious change in CD spectrum，indicating that HIFU might cause little effect on lysozyme lower structure. Whereas a weaken fluorescence intensity appeared indicating lysozyme conformation change. Data of SDS-PAGE showed obvious degradation of lysozyme branches. 1H-NMR analysis demonstrated that tryptophan（Trp） residue of lysozyme displayed chemical shift after treatment. Conclusion：The conformation structure of lysozyme could be changed by HIFU.