Chasovnikova L V, Matveeva N A, Lavrent'ev V V
Biofizika. 1980 Nov-Dec;25(6):984-8.
Dependence of surface denaturation kinetics of rabbit immunoglobulin G (IgG) in monomolecular layers at air-water interfaces on the substrate pH has been studied. By measuring the surface potential the drift of the isoelectric point of IgG in monolayer as compared to that of the bulk aqueous phase in the direction of high pH values has been demonstrated. The IgG molecule displays the greatest stability in monolayer at the isoelectric point. An increase of protein molecules positive charge in the region of 7.5--5.5 pH units is not sufficient for prominent acceleration of surface denaturation in comparison to the isoelectric point. A decrease of the substrate pH lower than 5.5 units is followed by the growth of the rate of surface denaturation which is directly proportional to [H+] concentration in the substrate. In the same region of pH values compensation of charges of protein molecules takes place, so that the surface potential is not changed and does not depend on the rate of molecular denaturation. High conformational stability of IgG molecules in monomolecular layers at air water interface has been confirmed.
研究了空气 - 水界面单分子层中兔免疫球蛋白G（IgG）的表面变性动力学对底物pH的依赖性。通过测量表面电位，已证明与本体水相相比，IgG在单分子层中的等电点向高pH值方向漂移。IgG分子在等电点的单分子层中表现出最大的稳定性。与等电点相比，在7.5 - 5.5 pH单位区域内蛋白质分子正电荷的增加不足以显著加速表面变性。底物pH降低到低于5.5单位时，表面变性速率增加，且与底物中[H⁺]浓度成正比。在相同的pH值区域内，蛋白质分子发生电荷补偿，因此表面电位不变且不依赖于分子变性速率。已证实空气 - 水界面单分子层中IgG分子具有高构象稳定性。
