脉冲电场对脂肪氧化酶活性及构象的影响

Effects of Pulsed Electric Field(PEF) on Activativity and Conformation Changes of Lipoxygenase(LOX)

为了解脉冲电场的钝酶机理,研究了高压脉冲电场处理对脂肪氧化酶(LOX)活性的影响。用圆二色谱和荧光分析法考察处理前后LOX构象变化的结果表明:PEF处理能够有效灭活LOX,且随着电场强度和处理时间的增加,灭活效果增加。CD光谱结果表明,PEF处理后LOX蛋白中α-螺旋的含量降低,而β-折叠含量增加,LOX二级构象发生变化。PEF处理后LOX的荧光发射增强,LOX的三级构象发生变化。

Lipoxygenases （LOX） （ EC 1.13.11.12） are widely distributed in nature. The presence of LOX activity in many foodstuffs can affect their properties, particularly during long-term storage, in both desirable and undesirable ways. So inactivation of LOX is a significant working procedure of processing, especially for shelf stable fruit juice. Inactivation of LOX by pulsed electric field （PEF） has been investigated in the present investigation. Circular dichroism （CD） and fluorescence analysis have been used to study the conformation change of the protein. The experimental results show that activity of LOX can be 88. 26 % reduced after a PEF treatment at 24 kV/cm for 962 μs. At the same tine, inactivation effect of LOX increases with the increase of the applied electric strength and treatment time. The circular dichroism （CD） analysis proved that α-helical and β-sheet simultaneously presented in the second conformation of LOX. In addition, pulsed electric field （PEF） treatment of LOX caused a loss of α-helix and increase of β-sbeet content, indicating that conformation changes occurred in the secondary structure of LOX enzyme. The fluorescence intensity of LOX increased after PEF treatment, at the same time, increase the applied electric field incrressed the fluorescence intensity emitted. These results prove local tertiary structure changes of LOX protein.