Blank M, Soo L, Britten J S
J Membr Biol. 1976 Nov 29;29(4):401-9. doi: 10.1007/BF01868973.
When mammalian sperm cells are exposed to solutions of albumin there are changes in the membranes of some species that resemble those that normally occur in the uterus prior to fertilization. We have shown that albumin molecules absorb on to the membranes of ejaculated rabbit sperm cells, and that the equilibrium binding constant, K, (1) varies inversely with the albumin concentration, (2) is independent of the sperm cell concentration in the range of 10(6)--10(7) per ml, (3) is independent of the time of exposure of the sperm cells to the albumin solution, and (4) decreases in the presence of Ca++ and Mg++ ions. An unusual aspect of the adsorption is that if the albumin concentration is given the symbol [A], K[A] is a constant in our measurements. This means that for virtually the entire range of [A] studied, the sperm cells bind albumin so that half of the available surface is coated and half remains uncoated. This situation is rather remarkable and it suggests a role that adsorption could play in the physical processes preceding fertilization. In purely physical systems, the optimum for the bridging and flocculation of particles that are coated with adsorbed macromolecular films occurs when half of the available surface is covered. The sperm cell appears to provide the optimal situation for interacting with itself or with another surface.
当哺乳动物的精子细胞暴露于白蛋白溶液时，某些物种的细胞膜会发生变化，这些变化类似于受精前子宫中正常发生的变化。我们已经表明，白蛋白分子会吸附在射出的兔精子细胞的膜上，并且平衡结合常数K：（1）与白蛋白浓度成反比；（2）在每毫升10⁶ - 10⁷个精子细胞的范围内与精子细胞浓度无关；（3）与精子细胞暴露于白蛋白溶液的时间无关；（4）在Ca²⁺和Mg²⁺离子存在时会降低。吸附的一个不寻常之处在于，如果用[A]表示白蛋白浓度，在我们的测量中K[A]是一个常数。这意味着在几乎整个研究的[A]范围内，精子细胞结合白蛋白，使得一半的可用表面被覆盖，另一半保持未被覆盖。这种情况相当显著，这表明吸附在受精前的物理过程中可能发挥的作用。在纯物理系统中，当一半的可用表面被覆盖时，对于被吸附的大分子膜覆盖的颗粒的桥连和絮凝来说是最佳的。精子细胞似乎为其自身或与另一个表面相互作用提供了最佳情况。
