PHYSICOCHEMICAL DIFFERENCES BETWEEN FRAGMENTS OF PLASMA MEMBRANE AND ENDOPLASMIC RETICULUM
PHYSICOCHEMICAL DIFFERENCES BETWEEN FRAGMENTS OF PLASMA MEMBRANE AND ENDOPLASMIC RETICULUM
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DOI：
10.1083/jcb.30.3.601
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发表时间：
1966-01-01
影响因子：
7.8
通讯作者：
GAIL, MH
中科院分区：
文献类型：
--
作者：
WALLACH, DFH;KAMAT, VB;GAIL, MH
测定了埃利希腹水癌细胞质膜和内质网碎片的比浊率、密度和折射率。建立了PM碎片的球壳模型，该模型具有特定的尺寸和折射率。系统地改变分散介质的离子组成。增加在[Gamma]/2引起的PM和ER悬浮液的浊度增加，最大的影响被观察到与Ca 2+和Mg 2+。在PM的情况下，这种效果主要是由于聚集，而“结构”的变化占大部分的浊度增加与ER。还系统地改变pH值，以获得pH-密度和浊度曲线，并确定2种膜类型的等电pH值（PM-3.6; ER[长划线]4.35）。在“等电”pH下，湍流最大，这在每种情况下对应于颗粒表面上的最小电荷区域。PM和ER两者在“等电”pH下均显示出密度的大幅增加，但在这些条件下仅ER显示出实质性的基于结构的浊度增加。PM和ER都显示在“等电”pH附近的静电吸引力。PM已被证明具有离子独特的内表面和外表面，而ER则没有这种不对称性。必要的理论背景解释浊度和密度测量，以及讨论我们的结论的局限性和我们的结果的生物学意义。
Specific turbidities, densities, and refractive indices of fragments of plasma membrane (PM) and endoplasmic reticulum (ER) from Ehrlich ascites carcinoma have been measured. A spherical shell model of specified dimensions and refractive index was established for PM fragments. The ionic composition of the dispersion medium was varied systematically. Increases in [GAMMA]/2 caused increases in the turbidity of both PM and ER suspensions, the greatest effects being observed with Ca2+ and Mg2+. In the case of PM this effect is attributable mainly to aggregation, whereas "structural" changes account for most of the turbidity increase with ER. The pH was also varied systematically to obtain pH-density and turbidity profiles and to establish the isoelectric pH of the 2 membrane types (PM-3.6; ER[long dash]4.35). Turbidity was maximum at "isoelectric" pH, which corresponds in each case to the region of minimum charge on the particle surfaces. Both PM and ER show large increases of density at the "isoelectric" pH, but only ER shows substantial structurally based turbidity increase under these conditions. Both PM and ER show operation of electrostatic attractions near "isoelectric" pH. PM has been shown to have ionically distinctive inner and outer surfaces while ER shows no such dissymmetry. The necessary theoretical background for interpretation of turbidity and density measurements is included, as well as a discussion of the limitations of our conclusions and the biological importance of our results.