Abstract

The role of furostanol glycosides (FGs) in the intensification of main metabolic processes in cultured yam (Dioscorea deltoidea Wall.) cells was shown. The effects of FGs were associated with changes in the complicated network of intracellular enzymatic reactions. This was evidenced by an increase in the activities of the enzymes from the glucose glycolytic oxidation pathway (hexokinase and fructose-1,6-difosphate aldolase) and the malate dehydrogenase complex (oxidoreductive—NADH/NAD-malate dehydrogenase and malic enzyme—decarboxylating NADP-malate dehydrogenase) as well as the stimulation of mitochondrial respiration accompanied by changes in activity of the alternative respiratory pathway. At the lag-phase of the growth cycle, the cell treatment with FGs was capable to guide glucose conversion through the glycolytic pathway. This was witnessed by a decrease in the activity of glucose-6-phosphate dehydrogenase and increase in that of hexokinase. Inhibition of NADPH oxidase afforded by diphenyliodonium chloride resulted in a decrease in activities of the key enzymes of glycolysis and the pentose phosphate cycle of glucose oxidation. Simultaneously, the aldolase activity increased and raised the content of its product glyceraldehyde 3-phosphate. The effect may explain the earlier-observed activation of the aldehyde-utilizing enzymes diminishing the initial POL level. The modulating action of FGs on activities of the enzymes of sugar glycolytic oxidation was shown. This was expressed as the activation of the tested enzymes at the lag- and exponential phases of the cellular growth and as the absence of the FG effect at the stationary phase. The short-term exposure of yam cells to FGs intensified the total mitochondrial respiration. An inhibitory analysis revealed the dominance of the cytochrome respiration pathway at the lag-phase, while its contribution became considerably lower at the later growth phases. FGs did not affect the rate of this respiration path but increased the potential activity of alternative oxidase (AO) during the lag- and exponential phases of the growth cycle. The FG-induced activation of AO, which may be intended to maintain a balance between carbohydrate metabolism and the rate of electron transport, is discussed.

中文翻译：

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呋喃固醇糖苷的作用下培养的山药细胞的呼吸道活性

摘要

呋喃固醇糖苷（FGs）在山药主要代谢过程中的作用（Dioscorea deltoidea显示了墙。FG的作用与细胞内酶促反应复杂网络的变化有关。葡萄糖糖酵解氧化途径中的酶（己糖激酶和果糖-1,6-二膦酸醛缩酶）和苹果酸脱氢酶复合物（氧化还原性NADH / NAD-苹果酸脱氢酶和苹果酸酶-脱羧化NADP）的酶活性增加证明了这一点。 -苹果酸脱氢酶）以及线粒体呼吸的刺激，伴随着另一种呼吸途径活性的改变。在生长周期的滞后阶段，用FG进行的细胞处理能够通过糖酵解途径指导葡萄糖转化。葡萄糖-6-磷酸脱氢酶活性降低而己糖激酶活性升高证明了这一点。氯化二苯基碘鎓提供的NADPH氧化酶的抑制导致糖酵解关键酶的活性降低和葡萄糖氧化的戊糖磷酸循环。同时，醛缩酶活性增加并提高了其产物3-磷酸甘油醛的含量。该作用可能解释了较早观察到的利用醛的酶的激活，降低了初始POL水平。显示了FG对糖酵解糖酵解酶活性的调节作用。这表示为被测试的酶在细胞生长的滞后和指数期的活化，并表现为在固定期不存在FG效应。山药细胞短期暴露于FGs会增强总线粒体呼吸作用。抑制性分析显示，细胞色素呼吸通路在滞后阶段占主导地位，而其贡献在后来的生长阶段变得相当低。FGs不会影响该呼吸路径的速率，但会在生长周期的滞后和指数期增加替代氧化酶（AO）的潜在活性。讨论了FG诱导的AO活化，该活化可能旨在维持碳水化合物代谢与电子传输速率之间的平衡。