Yang Yumin, Li Daojin
Department of Life Science, Luoyang Normal University, Luoyang, 471022, China.
College of Chemistry & Chemical Engineering, Luoyang Normal University, Luoyang, 471022, China.
Luminescence. 2016 Aug;31(5):1130-7. doi: 10.1002/bio.3082. Epub 2016 Jan 7.
The binding of isorhamnetin to bovine liver catalase (BLC) was first investigated at 302, 310 and 318 K at pH 7.4 using spectroscopic methods including fluorescence spectra, circular dichroism (CD) and UV-vis absorption. Spectrophotometric observations are rationalized mainly in terms of a static quenching process. The binding constants and binding sites were evaluated by fluorescence quenching methods. Enzymatic activity of BLC in the absence and presence of isorhamnetin was measured using a UV/vis spectrophotometer. The result revealed that the binding of isorhamnetin to BLC led to a reduction in the activity of BLC. The positive entropy change and enthalpy change indicated that the interaction of isorhamnetin with BLC was mainly driven by hydrophobic forces. The distance r between the donor (BLC) and acceptor (isorhamnetin) was estimated to be 2.99 nm according to fluorescence resonance energy transfer. Fluorescence, synchronous fluorescence, and CD spectra showed no obvious change in the conformation of BLC upon the binding of isorhamnetin. In addition, the influence of pH on the binding of isorhamnetin to BLC was investigated and the binding ability of the drug to BLC deceased under other pH conditions (pH 9.0, 6.5, 5.0, 3.5, or 2.0) as compared with that at pH 7.4. Copyright © 2016 John Wiley & Sons, Ltd.
首先在302、310和318 K温度、pH 7.4条件下，采用荧光光谱、圆二色性（CD）和紫外可见吸收等光谱方法，研究了异鼠李素与牛肝过氧化氢酶（BLC）的结合情况。分光光度观测结果主要通过静态猝灭过程进行合理解释。采用荧光猝灭法评估结合常数和结合位点。使用紫外可见分光光度计测量有无异鼠李素时BLC的酶活性。结果表明，异鼠李素与BLC的结合导致BLC活性降低。正的熵变和焓变表明，异鼠李素与BLC的相互作用主要由疏水作用力驱动。根据荧光共振能量转移，供体（BLC）和受体（异鼠李素）之间的距离r估计为2.99 nm。荧光光谱、同步荧光光谱和CD光谱显示，异鼠李素结合后BLC的构象没有明显变化。此外，研究了pH对异鼠李素与BLC结合的影响，与pH 7.4时相比，在其他pH条件（pH 9.0、6.5、5.0、3.5或2.0）下，该药物与BLC的结合能力降低。版权所有© 2016约翰威立父子有限公司。
