Verger R, Rietsch J, Desnuelle P
J Biol Chem. 1977 Jun 25;252(12):4319-25.
In a system free of bile salts we measured lipase hydrolysis of 1,3-didecanoylglycerol films in the presence or absence of colipase at different surface pressures. The strong, but not absolutely specific protective effect of colipase, most visible at low surface pressure, can account for the higher enzyme activity in the presence of colipase. This can be understood by taking into account simultaneous penetration and surface inactivation fluxes. Using radioactively labeled lipase, we have shown for the first time in a bile salt-free system that the critical surface pressure above which lipase can no longer penetrate a 1,2-didodecanoylphosphatidylglycerol monlayer is around 23 dynes/cm. Colipase increased this critical surface pressure to 30 dynes/cm indicating that it enables lipase penetration between 23 and 30 dynes/cm. The transfer experiment showed that colipase acts by first penetrating the lipid film and then serving as an anchor for lipase into the film.
在一个不含胆盐的体系中，我们测定了在不同表面压力下，有或没有辅脂酶存在时，脂肪酶对1,3 - 二癸酰甘油膜的水解作用。辅脂酶具有很强但并非绝对特异的保护作用，在低表面压力下最为明显，这可以解释在有辅脂酶存在时酶活性较高的现象。考虑到同时存在的渗透通量和表面失活通量，这一点是可以理解的。我们使用放射性标记的脂肪酶，首次在无胆盐体系中表明，脂肪酶无法再穿透1,2 - 二十二烷酰磷脂酰甘油单层的临界表面压力约为23达因/厘米。辅脂酶将这个临界表面压力提高到30达因/厘米，表明它能使脂肪酶在23至30达因/厘米之间穿透。转移实验表明，辅脂酶首先穿透脂质膜，然后作为脂肪酶进入膜的锚定物发挥作用。
