应用SRCD和FTIR分析超高压处理对蘑菇多酚氧化酶二级结构的影响

应用同步辐射紫外真空圆二色光谱(SRCD)、傅里叶变换红外光谱(FTIR)和荧光光谱研究了超高压(HHP)处理对蘑菇多酚氧化酶(PPO)二级结构和三级结构的影响。HHP处理使蘑菇PPO的α-螺旋含量明显减少,二级结构发生改变。通过SRCD光谱和FTIR光谱分析得出的未处理或HHP处理蘑菇PPO的二级结构含量均存在一定的差异,这种差异可能是由于测量温度、酶液浓度和分析方法等多种因素造成的。荧光光谱表明,HHP处理后,蘑菇PPO溶液荧光光谱的强度降低,最大发射峰发生了红移,表明HHP处理改变了蘑菇PPO分子的三级结构。

Study on the effect of high hydrostatic pressure treatment on the secondary structure of mushroom polyphenoloxidase by SRCD and FTIR

The secondary structure of the mushroom polyphenoloxidase treated by the high hydrostatic pressure (HHP) was analyzed by the synchrotron radiation circular dichroism (SRCD) and Fourier transform infrared spectroscopy (FTIR). The alpha-helix content of mushroom PPO was decreased after HHP treatment, which indicated that the secondary structure of PPO was changed. There was a discrepancy of the result of the secondary structure content between untreated or HHP-treated mushroom PPO analyzed by SRCD and FTIR spectra, and this discrepancy may be due to the different determination temperature, the concentration of the PPO solution and the spectra analysis method etc. The fluorescence spectra showed that the fluorescence intensity of the mushroom PPO was decreased after HHP treatment, and a red shift was observed after HHP treatment, which indicated that the tertiary structure of the enzyme molecule has been modified.