食品科学2018，Vol.39Issue(7)：146-152,7.DOI:10.7506/spkx1002-6630-201807022
AG9/AB9与牛血清白蛋白相互作用的德拜休克尔极限理论分析及其焓熵补偿
Interaction of AG9/AB9 with BSA: Analysis by Debye-Hückel Limiting Law and Observation of Enthalpy-Entropy Compensation
摘要
Abstract
Multispectral techniques were employed to detect salt concentration (i.e. ionic strength)-modulated interaction of acid green 9 (AG9) and acid blue 9 (AB9) with bovine serum albumin (BSA). The Debye-Hückel limiting law was applied to quantitative analysis to calculate the true Gibbs free energy change (ΔG0I→0) and effective charge (ZB) in the anion receptor pocket of BSA. The sign of ZCvalue for AG9/AB9 was negative and the ZBvalues were positive. These results indicated the formation of ion-pair between opposite charges; for example, the negatively charged AG9/AB9 bound to the net positively charged binding pocket (site-I) of BSA, suggesting that the local charge rather than the overall or surface charge of BSA played a key role in dominating the interaction strength of BSA-AG9/AB9 system. Moreover, with the increase of salt concentration, the entropy gradually varied from positive to negative and the exothermic enthalpy term increased so that the ΔG0was almost invariant, namely enthalpy-entropy compensation. Finally, the thermodynamic parameters changed from ΔH0< 0, ΔS0> 0 (electrostatic force) to ΔH0< 0, ΔS0< 0 (non-electrostatic force) at high salt concentration. These results showed that the mobility/local motion of AG9/AB9 complexed with protein was retarded due to the transformation of dominant force.关键词
酸性绿9/酸性蓝9/牛血清白蛋白/德拜休克尔极限理论/焓熵补偿Key words
acid green 9/acid blue 9/bovine serum albumin/Debye-Hückel theory/enthalpy-entropy compensation分类
轻工纺织引用本文复制引用
曹丽君,程正军,蒋晓慧..AG9/AB9与牛血清白蛋白相互作用的德拜休克尔极限理论分析及其焓熵补偿[J].食品科学,2018,39(7):146-152,7.基金项目
四川省科技厅应用基础项目(2016JY0080) （2016JY0080）
