Study on Interaction betweenYan-Hu-Ning and Bovine Serum Albumin by Spectrometry / 世界科学技术-中医药现代化

ABSTRACT

The interaction betweenYan-Hu-Ning (YHN) and bovine serum albumin (BSA) was investigated in order to provide further theoretical evidences on action mechanism study between YHN and proteins within the organism. Under optimal conditions, the interaction between YHN and BSA was studied by fluorescence quenching, ultraviolet absorption spectrometry and synchronous fluorescence spectroscopy. At the temperature of 283.15 K, 298.15 K and 313.15 K, quenching constant (KSV) and speed constant (Kq) were calculated by S-V curves. Static quenching constant (KLB) was obtained by L-B double reciprocal equation. Double logarithmic equation was used to calculate the binding constants (Kb) and the number of binding site (n). Thermodynamic equation was used to obtainΔH,ΔS,ΔG. Hill’s coefficients (nH) was obtained by Hill equation. The results showed that at three different temperatures, along with the increasing of YHN concentration, the fluorescence intensity of BSA decreased regularly. The value of KSV, Kq, KLB, Kb, n and nH decreased with the increasing of temperature;ΔG 1. It was concluded that YHN-BSA complex quenched the intrinsic fluorescence of BSA. The mechanism of fluorescence quenching was static quenching. The main binding forces were deduced as hydrogen bonds and Van der Waals forces from calculated values of thermodynamic parameters. YHN and BSA can form a binding site, which indicated certain binding interaction between YHN and BSA. YHN can be stored and transported by protein within the body. Free energy was produced to transformΔG into negative value. It showed that the process of binding between YHN and BSA was spontaneous. The nH was more than 1. It indicated that YHN had positive cooperative effect. The primary binding site was located at subdomainⅡA. The synchronous fluorescence spectra showed certain influence on the conformation of BSA by YHN. It led to the weakening of polarity within BSA and the binding site to be closer to the tyrosine.