Li Y, Gao F, Gao F, Shan F, Bian J, Zhao C
Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi Univ, Taiyuan, PR China.
J Food Sci. 2009 Apr;74(3):C199-203. doi: 10.1111/j.1750-3841.2009.01080.x.
The interaction between alpha-amylase and 3 flavonoid compounds from tartary buckwheat bran, namely, quercetin (Que), its monoglycoside isoquercetin (Iso), and its diglycoside rutinb (Rut), has been studied by fluorescence spectroscopy and enzymatic kinetics. The results indicate that Que, Iso, and Rut could bind with alpha-amylase to form a new complex, which exhibits an obvious fluorescence quenching. We deduce that such a quenching is a static quenching via nonradiation energy transfer. Results from plots and calculations show that the sequence of binding constants (KA) is Iso > Que > Rut. Calculation on thermodynamic parameters reveals that the main driving force of above-mentioned interaction is hydrophobic. Enzyme activity measurements show that all of the 3 flavonoid compounds are effective inhibitors toward alpha-amylase, and the inhibitory mode belongs to a competitive type. The sequence of affinity (1/Ki) is in accordance with the results of binding constants (KA) from fluorescence experiments.
通过荧光光谱法和酶动力学研究了α-淀粉酶与苦荞麸皮中的3种黄酮类化合物（槲皮素（Que）、其单糖苷异槲皮素（Iso）及其二糖苷芦丁（Rut））之间的相互作用。结果表明，Que、Iso和Rut可与α-淀粉酶结合形成新的复合物，呈现出明显的荧光猝灭。我们推断这种猝灭是通过非辐射能量转移的静态猝灭。图谱和计算结果表明，结合常数（KA）的顺序为Iso＞Que＞Rut。热力学参数计算表明，上述相互作用的主要驱动力是疏水作用。酶活性测定表明，这3种黄酮类化合物均是α-淀粉酶的有效抑制剂，抑制模式属于竞争型。亲和力顺序（1/Ki）与荧光实验中结合常数（KA）的结果一致。
