Davidson S J, Song S W
Biochim Biophys Acta. 1975 Jan 28;375(2):274-85. doi: 10.1016/0005-2736(75)90195-9.
Preparations of radioactive lysosomes were obtained from mouse kidney after injection of radioactive iodine-labeled bovine ribonuclease. Stability of these lysosomes in various media was estimated from measurements of proteolytic activity towards the ribonuclease, and of ribonuclease retention in particles. The lysosomes were stable at 37 degrees C in isotonic, sucrose-free solutions of KCl, NaCl, and potassium acetate, and in mixtures of these with MgCl2, showing that these salts are relatively impermeant through the lysosomal membranes. The membranes were less permeable to Na+ than to K+. Both KCl and NaCl exerted their optimal protective effects over a broad concentration range above 0.125 M in 0.025 M acetate buffer. Mg2+ enhanced the protective effect of both K4 and Na+; the osmotic effect of 0.075 M NaC1-0.05 M MgCl2 was indistinguishable during the entire course of ribonuclease digestion from that of isotonic sucrose. Osmotic protection by KC1-MgC12 was demonstrated over the H range5.5-7.0. A marked alteration in membrane properties occurs at lower temperatures in 0.11 M KC1-0.01 M MgCl2 such that, at 0 degrees C, K+ permeability is much higher than at 37 degrees C, as shown by a several-fold decrease in stability at the lower temperature.
在注射放射性碘标记的牛核糖核酸酶后，从小鼠肾脏获得放射性溶酶体的制剂。通过测量对核糖核酸酶的蛋白水解活性以及核糖核酸酶在颗粒中的保留情况，评估这些溶酶体在各种介质中的稳定性。溶酶体在37℃时，在等渗的无蔗糖的氯化钾、氯化钠和醋酸钾溶液中，以及在这些溶液与氯化镁的混合物中是稳定的，这表明这些盐相对不易透过溶酶体膜。膜对钠离子的通透性比对钾离子的通透性低。在0.025M醋酸盐缓冲液中，氯化钾和氯化钠在高于0.125M的较宽浓度范围内都发挥了最佳保护作用。镁离子增强了钾离子和钠离子的保护作用；在核糖核酸酶消化的整个过程中，0.075M氯化钠 - 0.05M氯化镁的渗透作用与等渗蔗糖的渗透作用没有区别。氯化钾 - 氯化镁在pH范围5.5 - 7.0内表现出渗透保护作用。在0.11M氯化钾 - 0.01M氯化镁中，较低温度下膜性质会发生明显改变，例如在0℃时，钾离子通透性比37℃时高得多，这表现为在较低温度下稳定性下降了几倍。
