Oliver A E, Fisk E, Crowe L M, de Araujo P S, Crowe J H
Section of Molecular and Cellular Biology, University of California, Davis 95616, USA.
Biochim Biophys Acta. 1995 Jun 20;1267(2-3):92-100. doi: 10.1016/0167-4889(95)90001-w.
In the presence of excess water, enzymatic activity of phospholipase A2 (PLA2) depends on the physical state of the lipid substrate. In order to determine if this also holds true in dehydrated systems, the physical parameters of charge, hydration state, and head group spacing of liposome membranes and their effects on PLA2 lipid hydrolysis were studied. Liposomes of varying composition were freeze-dried in the presence of PLA2 and partially rehydrated at controlled relative humidities. Accumulation of free fatty acids in the liposomal membranes was used as a measure of PLA2 activity. We found that PLA2, which was not activated during lyophilization, was most active during partial rehydration of the liposomes. The hydration state, charge and headgroup spacing of the membrane were all important in determining PLA2 activity in the dehydrated system.
在存在过量水的情况下，磷脂酶A2（PLA2）的酶活性取决于脂质底物的物理状态。为了确定在脱水系统中是否也是如此，研究了脂质体膜的电荷、水合状态和头部基团间距等物理参数及其对PLA2脂质水解的影响。将不同组成的脂质体在PLA2存在下冻干，并在控制的相对湿度下进行部分再水化。脂质体膜中游离脂肪酸的积累用作PLA2活性的指标。我们发现，在冻干过程中未被激活的PLA2在脂质体部分再水化过程中活性最高。膜的水合状态、电荷和头部基团间距在确定脱水系统中的PLA2活性方面都很重要。
