DETACHMENT OF AGGLUTININ-BONDED RED-BLOOD-CELLS .1. FORCES TO RUPTURE MOLECULAR-POINT ATTACHMENTS
DETACHMENT OF AGGLUTININ-BONDED RED-BLOOD-CELLS .1. FORCES TO RUPTURE MOLECULAR-POINT ATTACHMENTS
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DOI：
10.1016/s0006-3495(91)82296-2
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发表时间：
1991-04-01
影响因子：
3.4
通讯作者：
LEUNG, A
中科院分区：
文献类型：
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作者：
EVANS, E;BERK, D;LEUNG, A
一个简单的微观力学方法已被开发来测量两个宏观光滑的膜囊之间的分子点连接（焦点键）的断裂强度。 在该过程中，制备一个具有低密度粘附分子覆盖的胶囊，形成为刚性球体，并通过微量移液管保持在固定位置。 不含粘附分子的第二个胶囊通过另一个移液管以低吸力加压成球形。 该胶囊被固定以在与刚性胶囊相对的极处引发点接触，这导致形成几个（甚至一个）分子附着。 然后，通过移液器的位移缓慢地抽出可变形胶囊。 分析表明，胶囊的端到端延伸提供了点接触处的力的直接测量，因此，当分离发生时，提供了破裂强度。 该技术可获得的点力的范围取决于膜的弹性模量、膜张力和囊的大小。 对于生物和合成囊泡膜，力的范围在10（-7）-10（-5）dyn（10（-12）-10（-10）N）之间，比目前原子力显微镜可测量的力小100倍！在这里，该方法被用来研究所需的力量，以打破红细胞膜血型糖蛋白，抗A血清，从蜗牛螺旋pomatia凝集素的单克隆抗体形成的红细胞之间的显微附件。 附件失效似乎是解脱力大小和持续时间的随机函数。 我们已经将观察到的破裂的统计行为与少量分子附着失效的随机过程模型相关联。 测量和分析的令人惊讶的结果是，对于1-2个分子附着的短时间失效推断的力对于所有凝集素几乎相同，即，1-2 x 10（-6）达因 因此，进行了显微荧光测试，以确定在分离大面积粘合剂接触后，标记的凝集素和/或标记的表面分子是否在表面之间转移。 结果表明，由于受体从膜中被提取，附着失败。
A simple micromechanical method has been developed to measure the rupture strength of a molecular-point attachment (focal bond) between two macroscopically smooth membrane capsules. In the procedure, one capsule is prepared with a low density coverage of adhesion molecules, formed as a stiff sphere, and held at fixed position by a micropipette. The second capsule without adhesion molecules is pressurized into a spherical shape with low suction by another pipette. This capsule is maneuvered to initiate point contact at the pole opposite the stiff capsule which leads to formation of a few (or even one) molecular attachments. Then, the deformable capsule is slowly withdrawn by displacement of the pipette. Analysis shows that the end-to-end extension of the capsule provides a direct measure of the force at the point contact and therefore, the rupture strength when detachment occurs. The range for point forces accessible to this technique depends on the elastic moduli of the membrane, membrane tension, and the size of the capsule. For biological and synthetic vesicle membranes, the range of force lies between 10(-7)-10(-5) dyn (10(-12)-10(-10) N) which is 100-fold less than presently measurable by Atomic Force Microscopy! Here, the approach was used to study the forces required to rupture microscopic attachments between red blood cells formed by a monoclonal antibody to red cell membrane glycophorin, anti-A serum, and a lectin from the snail-helix pomatia. Failure of the attachments appeared to be a stochastic function of the magnitude and duration of the detachment force. We have correlated the statistical behavior observed for rupture with a random process model for failure of small numbers of molecular attachments. The surprising outcome of the measurements and analysis was that the forces deduced for short-time failure of 1-2 molecular attachments were nearly the same for all of the agglutinin, i.e., 1-2 x 10(-6) dyn. Hence, microfluorometric tests were carried out to determine if labeled agglutinins and/or labeled surface molecules were transferred between surfaces after separation of large areas of adhesive contact. The results showed that the attachments failed because receptors were extracted from the membrane.