Tsujita T, Okuda H
Department of Medical Biochemistry, School of Medicine, Ehime University.
J Biochem. 1992 Aug;112(2):224-8. doi: 10.1093/oxfordjournals.jbchem.a123881.
The activity of phospholipase C from Clostridium perfringens on 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) as a monolayer at an air/water interface was examined. With a pure POPC monolayer, sharp cut-off of the enzyme activity was observed on increase in surface pressure. However, this cut-off disappeared on addition of a 0.3 molar fraction of 1,2-dioleoylglycerol (1,2-DO) to the monolayer. An abrupt change in the enzyme activity was observed with molar fractions of between 0.2 and 0.3 1,2-DO in the POPC monolayer at an initial surface pressure of 35 mN/m. For examination of the effect of 1,2-DO on the phospholipase C activity, the quantity of [125I]phospholipase C adsorbed to the surface was determined. The enzyme was found to be adsorbed nonspecifically to all lipid films except that of POPC only. The adsorption of enzyme was not affected by the presence or absence of Ca2+ and Zn2+. The rate constant for enzyme adsorption to a 1,2-DO film was 4.5 times that for its adsorption to a POPC film. The adsorption decreased linearly with increase in the surface concentration of POPC, and increased with increase in the surface concentration of 1,2-DO. These data suggest that 1,2-DO (a reaction product) regulates the interaction of phospholipase C with films containing substrate and may also regulate the enzyme activity.
研究了产气荚膜梭菌的磷脂酶C对1-棕榈酰-2-油酰-sn-甘油-3-磷酸胆碱（POPC）在空气/水界面形成的单层膜的活性。对于纯POPC单层膜，随着表面压力增加，酶活性出现明显的截止现象。然而，当向单层膜中添加摩尔分数为0.3的1,2-二油酰甘油（1,2-DO）时，这种截止现象消失。在初始表面压力为35 mN/m的POPC单层膜中，当1,2-DO的摩尔分数在0.2至0.3之间时，观察到酶活性发生突然变化。为了研究1,2-DO对磷脂酶C活性的影响，测定了吸附在表面的[125I]磷脂酶C的量。发现该酶能非特异性地吸附到除仅含POPC的脂质膜以外的所有脂质膜上。酶的吸附不受Ca2+和Zn2+存在与否的影响。酶吸附到1,2-DO膜上的速率常数是其吸附到POPC膜上速率常数的4.5倍。吸附量随POPC表面浓度的增加呈线性下降，随1,2-DO表面浓度的增加而增加。这些数据表明，1,2-DO（一种反应产物）调节磷脂酶C与含底物的膜之间的相互作用，并且可能也调节酶活性。
