Bianco I D, Fidelio G D, Maggio B
Departamento de Quimica Biológica, CIQUIBIC, Facultad de Ciencias Químicas, CONICET, Universidad Nacional de Cordoba, Argentina.
Biochim Biophys Acta. 1990 Jul 24;1026(2):179-85. doi: 10.1016/0005-2736(90)90062-s.
The effect of sulfatide and gangliosides GM1, GD1a and GT1b on the activity of phospholipase C from Clostridium perfringens on dilauroylphosphatidylcholine and of porcine pancreatic phospholipase A2 on dilauroylphosphatidic acid was studied in lipid monolayers containing different proportions of glycolipids under zero-order kinetics at various constant surface pressures. The presence of sulfatide in the monolayer increases the activity of phospholipase C at high surface pressures. Gangliosides shift the cut-off pressure to lower values and inhibit the action of phospholipase C. In mixed monolayers with dilauroylphosphatidic acid, sulfatide at a molar fraction of 0.5 increases the activity of phospholipase A2 at surface pressures below 18 mN/m and shows an inhibitory effect at higher pressures. Ganglioside GM1 at a molar fraction of 0.25 completely inhibits the enzyme above 20 mN/m and markedly reduces its activity at lower pressures. Gangliosides GD1a and GT1b abolish the enzyme activity at all pressures at molar fractions of 0.25 and 0.15, respectively. The modified velocity of the enzymatic reaction in the presence of glycosphingolipids is not due to an irreversible alteration of the catalytic activity.
研究了硫苷脂和神经节苷脂GM1、GD1a和GT1b对产气荚膜梭菌磷脂酶C作用于二月桂酰磷脂酰胆碱的活性以及猪胰磷脂酶A2作用于二月桂酰磷脂酸的活性的影响。在不同恒定表面压力下的零级动力学条件下，于含有不同比例糖脂的脂质单分子层中进行了上述研究。单分子层中硫苷脂的存在会在高表面压力下提高磷脂酶C的活性。神经节苷脂会将截止压力移至较低值并抑制磷脂酶C的作用。在与二月桂酰磷脂酸的混合单分子层中，摩尔分数为0.5的硫苷脂在表面压力低于18 mN/m时会提高磷脂酶A2的活性，而在较高压力下则表现出抑制作用。摩尔分数为0.25的神经节苷脂GM1在高于20 mN/m时会完全抑制该酶，并在较低压力下显著降低其活性。神经节苷脂GD1a和GT1b在摩尔分数分别为0.25和0.15时，在所有压力下都会消除该酶的活性。在存在鞘糖脂的情况下，酶促反应的修正速度并非由于催化活性的不可逆改变。
