Raicu V, Raicu G, Turcu G
Romanian Academy, Institute of Physical Chemistry, Department of Colloids, Bucharest, Romania.
Biochim Biophys Acta. 1996 Jun 13;1274(3):143-8. doi: 10.1016/0005-2728(96)00024-2.
The paper reports a re-evaluation of the previous studies on yeast by considering the influence of vacuole upon the dielectric properties of the cell. In this respect, relative permittivity and conductivity of yeast cells dispersed in KCI solutions of various concentrations were measured in the frequency range from 0.1 to 100 MHz. The analysis of data revealed that the beta-dielectric dispersion of yeast cell suspensions is a composite of three (or probably four) distinct sub-dispersions. Since the dielectric response of the cell wall was experimentally avoided (according to Asami et al. (1976) J. Membr. Biol. 28, 169-180), the two-shell model, related to the plasma membrane and the vacuolar membrane, respectively, appeared to be the best approximation for yeast cells. The most relevant parameters obtained with the aid of the two-shell model were as follows. Specific capacitance of the plasma membrane and the vacuolar membrane were 0.703 +/- 0.011 microF/cm2 and 0.483 +/- 0.029 microF/cm2, respectively; electrical conductivity of the cytoplasm and the vacuole interior were 0.515 +/- 0.028 S/m and 3.22 +/- 0.48 S/m; finally, the permittivity of the cytoplasm was 50.6 +/- 2.
本文通过考虑液泡对细胞介电特性的影响，对先前关于酵母的研究进行了重新评估。在这方面，测量了分散在不同浓度氯化钾溶液中的酵母细胞在0.1至100 MHz频率范围内的相对介电常数和电导率。数据分析表明，酵母细胞悬浮液的β-介电色散是三个（或可能四个）不同子色散的组合。由于通过实验避免了细胞壁的介电响应（根据浅见等人（1976年）《膜生物学杂志》28卷，第169 - 180页），分别与质膜和液泡膜相关的双壳模型似乎是酵母细胞的最佳近似模型。借助双壳模型获得的最相关参数如下。质膜和液泡膜的比电容分别为0.703±0.011 μF/cm²和0.483±0.029 μF/cm²；细胞质和液泡内部的电导率分别为0.515±0.028 S/m和3.22±0.48 S/m；最后，细胞质的介电常数为50.6±2。
