【摘要】 用差示扫描量热法(DSC)和荧光光谱法研究了L-半胱氨酸(L-Cys)与牛血清白蛋白(BSA)在一定离子强度的Tris-HCl缓冲溶液中的相互作用,发现随着L-Cys浓度的增大,BSA的DSC热转变曲线峰形变宽变平,变性温度(tm)和变性焓(ΔHm)降低,说明L-Cys的加入使BSA分子的高级结构发生了变化,稳定性降低。荧光强度也随着L-Cys浓度的增大而减小,符合Stern-Volmer方程F0/F=1.0143+1.4447c,表现为规律性的动态猝灭;而最大发射波长(λmax)先变小再增大,即先蓝移后红移,表明L-Cys的加入使BSA分子中Trp荧光残基所处的微环境发生了复杂的变化。更多还原

【Abstract】 The two methods of DSC and fluorescence spectroscopy were combined to investigate the interactions between L-cysteine(L-Cys) and bovine serum albumin(BSA) Tris-HCl buffer solutions at given ionic strength.It was found that the profiles of thermal transition curves of BSA become broader and shallower,and the transition temperatures(tm) and transition enthalpies(ΔHm) decrease as the concentrations of L-Cys increase,which demonstrates that the addition of L-Cys makes the higher structure of BSA molecule changed and lowers the stability of it.The strength of fluorescence is also found to become decrease on increasing concentration of L-Cys.The quenching is dynamic regularly and follows the Stern-Volmer equation,F0/F=1.0143+1.4447c,where L-Cys is considered to be a quenching agent.The maximal emission wavelength(λmax) becomes smaller at first and then increases,that is,blue shift occurs first and then red shift,which demonstrates that the microenvironment of fluorescent residue Trp in BSA changes complicatedly as the addition of L-Cys.更多还原