关键词:

β-环糊精, 多酚氧化酶, 催化, 邻苯二酚, 反应动力学

Abstract:

Two kinds of β-cyclodextrin (β-CD) derivatives mono-6-(N-histamino)-6-deoxy-β-cyclodextrin (6-His-β-CD) and mono-2-(N-histamino)-2-deoxy-β-cyclodextrin (2-His-β-CD) were prepared by reacting β-CD withp-toluene sulfonyl chloride, displacement the monotosylate with iodide, and finally the reaction of cyclodextrin iodide with nucleophile L-histidine.From these derivatives, the β-CD-Cu(Ⅱ) complexes (Cu(Ⅱ)/6-His-β-CD， Cu(Ⅱ)/2-His-β-CD) with polyphenol oxidase (PPO) activity were synthesized.The derivatives and the complexes were characterized with elemental analysis, Fourier-transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and atomic absorption spectrometry.The complexes were used as catalysts for the oxidation of catechol using O₂ as the oxidant, which was monitored by UV-Vis spectrophotometer.The effects of temperature and pH value on the reaction were also studied.The results indicated that the PPO mimics exhibited high catalytic activities.Cu(Ⅱ)/2-His-β-CD showed higher PPO activity than Cu(Ⅱ)/6-His-β-CD.The kinetic studies showed that all three factors, the hydrophobic environment provided by β-CD, the Cu(Ⅱ) bound to the histamine and the base catalysis contributed to the PPO activity.

Key words:

β-环糊精, 多酚氧化酶, 催化, 邻苯二酚, 反应动力学