Pectinmethylesterase (PME) is a degradative enzyme of the cloudiness of fruit juices. Pulsed light (PL) is a non-thermal technology able to inactivate enzymes. This work aimed to assess the potential inactivation of PME by PL and to explain how it occurs. To this, a suspension of the enzyme was treated with PL up to 128 J/cm². The inactivation curve was built and structural changes were determined by far-UV circular dichroism, intrinsic and extrinsic fluorescence and spectrophotometry. Furthermore, the presence/absence of unfolding intermediaries was assessed by phase-diagram analysis. PL was able to inactivate PME with a first-order kinetic rate of 0.034 cm²/J. The inactive protein seemed to have a molten-globule structure, due to the conserved secondary structure and modified tertiary structure. Phase diagram data fitted a single line, which is consistent with absence of unfolding intermediaries. A significant increase in absorbance at 420 nm (p < 0.05) showed that PL promoted enzyme aggregation.

果胶甲酯酶（PME）是果汁浑浊的降解酶。脉冲光（PL）是一种能够灭活酶的非热技术。这项工作旨在评估PL对PME的潜在灭活作用，并解释其如何发生。为此，用PL将酶的悬浮液处理至128J / cm ²。建立了灭活曲线，并通过远紫外圆二色性，内在和外在荧光以及分光光度法确定了结构变化。此外，通过相图分析评估了展开中间体的存在与否。PL能够以0.034 cm ^2的一级动力学速率灭活PME。/ J。由于保守的二级结构和修饰的三级结构，无活性的蛋白质似乎具有熔融小球结构。相图数据拟合为一条线，这与没有展开的中介相一致。420 nm处吸光度的显着增加（p <0.05）表明PL促进了酶的聚集。