非电解质的流动和胡萝卜根组织细胞的区室化。
Fluxes of a nonelectrolyte and compartmentation in cells of carrot root tissue.
机构信息
Department of Botany, Tel Aviv University, Tel Aviv, Israel.
出版信息
Plant Physiol. 1974 Feb;53(2):307-11. doi: 10.1104/pp.53.2.307.
Permeation of thiourea into cells of carrot (Daucus carota L.) storage root discs was found to be governed by its concentration gradient only. The analysis of the course of thiourea efflux from preloaded discs shows two distinct exponential curves, apart from an initial very fast component. Reasons are given for relating the first exponential part of the curve to efflux from the cytoplasm and the second exponential part to efflux from the vacuole.The rate constant for thiourea efflux through the tonoplast is markedly temperature-dependent (activation energy 13.2 kcal mole(-)) and is lowered by 2,4-dinitrophenol and by phenyl mercuric acetate treatments. The rate constant for its efflux through the plasmalemma, on the other hand, has a low activation energy (4.2 kcal mole(-)), which is equal to that of free diffusion of thiourea in aqueous solution, and is not affected by the metabolic inhibitors. Possible reasons for the difference in the properties of the two membranes are discussed.
硫脲进入胡萝卜（Daucus carota L.）贮藏根圆盘细胞的渗透仅受其浓度梯度的控制。对预加载圆盘内硫脲流出过程的分析表明，除了最初非常快的成分外，还有两个明显的指数曲线。给出了将曲线的第一个指数部分与细胞质流出以及第二个指数部分与液泡流出相关联的原因。硫脲通过液泡被膜的流出速率常数明显依赖于温度（活化能为 13.2 kcal mole(-)），并且被 2,4-二硝基苯酚和苯汞乙酸盐处理降低。另一方面，其通过质膜的流出速率常数具有低的活化能（4.2 kcal mole(-)），这与硫脲在水溶液中的自由扩散相等，并且不受代谢抑制剂的影响。讨论了两种膜性质差异的可能原因。
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