SCCO_2处理对PPO分子特性及构象的影响

Molecular properties and conformational changes of PPO by SCCO_2

研究超临界二氧化碳(SCCO2)对多酚氧化酶(PPO)分子特性及构象的影响。采用SCCO2和温度协同处理PPO酶,并用透射电镜、SDS-PAGE电泳、圆二色谱和荧光光谱分析PPO酶分子形态、一级、二级和三级结构变化。结果表明:SCCO2技术处理后,PPO酶蛋白分子直径变大;PPO酶一级结构未发生变化;其二级和三级结构受到影响:随着压力和温度的增加,α-螺旋含量逐渐降低,经65℃、35MPa处理30min后,α-螺旋含量降至31.43%;PPO的荧光光谱也发生了变化,表现为谱图峰位,峰型以及荧光强度的变化。

In order to study the effects of supercritical carbon dioxide（SCCO2）on the molecular properties and conformational changes of polyphenol oxidase（PPO）,the SCCO2and temperature synergistic treatment were carried out on the PPO.And the molecular properties and conformational changes were analyzed using transmission electronic microscope,SDS-PAGE,far UV-circular dichroism and fluorescence spectroscopy.It was shown that the aggregation of PPO molecules was suggested by an increase in the particle size of PPO after SCCO2treatment,but the electrophoretic behavior of PPO was not altered on the SDS-PAGE.The CD and fluorescence spectra of SCCO2-treated PPO were noticeably changed,itsα-helix relative content decreased sharply to 31.43%after 30mins treatment at 65 ℃、35MPa,and the peak position,peak shape and intrinsic fluorescence intensity changed obviously.