Engel J, Pastushenko V F, Richter W, Donath E
Humboldt University, Department of Biology, Berlin, G.D.R.
Biorheology. 1991;28(1-2):75-87. doi: 10.3233/bir-1991-281-208.
We present a model for the calculation of intragranular vesicle adhesion energy in a two-vesicle system consisting of an external secretory vesicle (chromaffin granule) and an intragranular vesicle (IGV) that adheres from the inside to the granule membrane. The geometrical parameters characterizing the granule-IGV systems were derived from freeze-fracture electron micrographs. Adhesion is brought about by incubation of the granules in hyperosmolar sucrose solutions. It is accompanied by a deformation of the granule because the intragranular vesicle bulges it outwards, and by segregation of intramembraneous particles from the adherent part of the granule membrane. Adhesion prevents the deformed granules from osmotic reexpansion and, therefore, causes hyperosmotic relaxation lysis. We estimated specific adhesion energy at -3 erg/cm2, a value which is 10 - 1000 times larger than the energy of van der Waals interaction between membranes. This large interaction energy probably results from changes of the granule core induced by dehydration. A minimization of the interface between the granule core and adjacent membranes could exclude intragranular vesicles from the core and squeeze them towards the granule membrane. This might induce a new kind of interaction between both membranes, which is irreversible and causes lysis upon osmotic relaxation.
我们提出了一个模型，用于计算由外部分泌囊泡（嗜铬颗粒）和从内部粘附于颗粒膜的颗粒内囊泡（IGV）组成的双囊泡系统中的颗粒内囊泡粘附能。表征颗粒 - IGV系统的几何参数源自冷冻蚀刻电子显微照片。通过将颗粒在高渗蔗糖溶液中孵育来实现粘附。这伴随着颗粒的变形，因为颗粒内囊泡使其向外凸出，并且伴随着颗粒膜粘附部分的膜内颗粒的分离。粘附阻止变形的颗粒进行渗透再膨胀，因此导致高渗松弛裂解。我们估计比粘附能为-3尔格/平方厘米，该值比膜之间的范德华相互作用能大10 - 1000倍。这种大的相互作用能可能是由脱水引起的颗粒核心变化导致的。颗粒核心与相邻膜之间界面的最小化可以将颗粒内囊泡从核心中排除，并将它们挤向颗粒膜。这可能会在两个膜之间诱导一种新的相互作用，这种相互作用是不可逆的，并在渗透松弛时导致裂解。
