莲藕多酚氧化酶与底物或抑制剂相互作用的光谱学研究

Spectroscopic Study on the Interaction of Substrates or inhibitors and Polyphenol Oxidase from Lotus Roots

本文研究了纯化的莲藕多酚氧化酶(PPO)与底物和抑制剂相互作用时的二级结构变化。园二色谱分析表明莲藕PPO主要含有α-螺旋和β-折叠结构。与抑制剂作用后,莲藕PPO活性显著降低,同时伴随其二级结构中α-螺旋结构明显减少,表明莲藕PPO的活性中心可能位于α-螺旋结构中。荧光分析表明,莲藕PPO与邻苯三酚(pyrogallic acid,PA)作用后,酪氨酸残基荧光强度略有降低,λmax位移不明显,色氨酸残基荧光强度略有降低,λmax红移2 nm;而与莲藕多酚(Lotus root polyphenol,LRP)作用后,莲藕PPO分子中酪氨酸(Tyr)和色氨酸(Trp)残基荧光强度显著提高,且其最大发射波长分别蓝移6nm和红移5nm。当加入异Vc钠后,Tyr和Trp残基最大发射峰显著红移,说明Trp和Tyr残基位于一定的疏水环境对维持PPO催化活性的优势构象至关重要。

Circular dichroism and fluorescence spectroscopy have been employed to study the secondary structure changes of polyphenol oxidase interacting with substrates or inhibitors.The results showed that PPO from lotus root has mostly α-helix and β-sheet structure.When it was mixed with substrate,the α-helix structure decreased sharply.The activity of the PPO decreased significantly accompanied by a significant decrease in α-helix structure when it was mixed with inhibitors,which implied that the active site of PP...