Albro P W, Hall R D, Corbett J T, Schroeder J
Biochim Biophys Acta. 1985 Jul 31;835(3):477-90. doi: 10.1016/0005-2760(85)90117-1.
The enzyme nonspecific lipase (EC 3.1.1.-) from rat pancreas has been isolated and its amino acid composition determined. The amino acid composition confirms more indirect evidence that nonspecific lipase is not the same enzyme as cholesteryl ester hydrolase. Activation of the enzymatic activity by bile salts has been studied by equilibrium dialysis, gel filtration, light scattering, circular dichroism and fluorescence polarization. The binding of bile salt by the enzyme is saturable and is associated with a conformational change. Upon binding cholate, the protein experiences a decrease in beta-structure with no significant change in alpha-helix content, an increase in apparent Stokes radius, a decrease in light scattering properties, and a slight decrease in polarization of the intrinsic tryptophan fluorescence. Attachment of bile salt is associated with decreased reactivity of essential sulfhydryl groups, but no detectable change in reactivity of amino groups. A change to a more nearly spherical shape upon binding bile salt would be consistent with the experimental observations, but the exact sites of binding remain uncertain.
已从大鼠胰腺中分离出非特异性脂肪酶（EC 3.1.1.-）并测定了其氨基酸组成。氨基酸组成证实了更多间接证据，表明非特异性脂肪酶与胆固醇酯水解酶不是同一种酶。已通过平衡透析、凝胶过滤、光散射、圆二色性和荧光偏振研究了胆汁盐对酶活性的激活作用。酶与胆汁盐的结合是可饱和的，并且与构象变化有关。结合胆酸盐后，蛋白质的β-结构减少，α-螺旋含量无显著变化，表观斯托克斯半径增加，光散射特性降低，内在色氨酸荧光的偏振略有降低。胆汁盐的附着与必需巯基的反应性降低有关，但氨基的反应性没有可检测到的变化。结合胆汁盐后变为更接近球形的形状与实验观察结果一致，但确切的结合位点仍不确定。
