Aggregation of porcine pancreatic phospholipase A2 and Its zymogen induced by submicellar concentrations of negatively charged detergents.
Aggregation of porcine pancreatic phospholipase A2 and Its zymogen induced by submicellar concentrations of negatively charged detergents.
复制标题
亚胶束浓度的带负电荷的去垢剂诱导猪胰磷脂酶 A2 及其酶原的聚集。
作者：
J. Hille;M. Egmond;R. Dijkman;M. V. van Oort;B. Jirgensons;G. de Haas
采用多种光谱技术、平衡凝胶过滤、量热法和光化学诱导动态核极化1H NMR研究了两种正烷基磺酸钠（C10和C12）与猪胰磷脂酶A2及其酶原的相互作用。在极低浓度的正烷基硫酸盐（高达0.07 X临界胶束浓度（cmc））下，酶（Mr 14000）能够与分子量约为90000的洗涤剂分子建立复合物。该络合物由6个酶分子和约40个正烷基硫酸盐单体组成。洗涤剂-蛋白质聚集体的形成发生在两个步骤的过程中：首先，两个洗涤剂分子强烈结合到蛋白质的疏水表面区域，以前称为界面识别位点[Pieterson， W. a ., Vidal， J. C., Volwerk， J. J., & de Haas， G. H.（1974）生物化学13,1455-1460]。随后，在较高的洗涤剂浓度下，6个酶分子突然聚集，可能包括约30个额外的洗涤剂单体。虽然胰磷脂酶A2的酶原似乎与这些洗涤剂形成相当的高分子量聚集体，但存在光谱差异，并且需要更高的洗涤剂浓度。此外，正如下面的论文[Hille， J. D. R., Egmond， M. R., Dijkman， R., van Oort， M. G., Sauve， P., & de Haas， G. H.（1983）《生物化学》（本期的下一篇论文）]所显示的那样，只有磷脂酶A2在这些复合物中被超激活。
The interaction of two sodium n-alkyl sulfates (C10 and C12) with porcine pancreatic phospholipase A2 and its zymogen was studied by various spectroscopic techniques, equilibrium gel filtration, calorimetry, and photochemically induced dynamic nuclear polarization 1H NMR. At very low concentrations of n-alkyl sulfate [up to 0.07 X critical micelle concentration (cmc)] the enzyme (Mr 14 000) is able to build up a complex with the detergent molecules having a molecular weight of about 90 000. This complex consists of 6 enzyme molecules and about 40 n-alkyl sulfate monomers. The formation of the detergent-protein aggregate occurs in a two-step process: First, two detergent molecules strongly bind to a hydrophobic surface region of the protein, previously called interface recognition site [Pieterson, W. A., Vidal, J. C., Volwerk, J. J., & de Haas, G. H. (1974) Biochemistry 13, 1455-1460]. Subsequently, at higher detergent concentrations suddenly 6 enzyme molecules aggregate, probably including about 30 additional detergent monomers. Although the zymogen of the pancreatic phospholipase A2 seems to form comparable high molecular weight aggregates with these detergents, there are spectroscopic differences, and higher detergent concentrations are required. Moreover, as will be shown in the following paper [Hille, J. D. R., Egmond, M. R., Dijkman, R., van Oort, M. G., Sauve, P., & de Haas, G. H. (1983) Biochemistry (following paper in this issue)], only the phospholipase A2 becomes superactivated in these complexes.