Enzymes of the ascorbate biosynthesis and ascorbate-glutathione cycle in cultured cells of tobacco Bright Yellow 2
Enzymes of the ascorbate biosynthesis and ascorbate-glutathione cycle in cultured cells of tobacco Bright Yellow 2
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DOI：
10.1016/s0981-9428(00)00773-7
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发表时间：
2000-07-01
影响因子：
6.5
通讯作者：
De Gara, L
中科院分区：
文献类型：
--
作者：
de Pinto, MC;Tommasi, F;De Gara, L
研究了烟草（Nicotiana tabacum cv.）亮黄2（TBY-2）细胞。发现TBY-2细胞被赋予L-半乳糖酸-γ-内酯脱氢酶（GLDH）（EC 1.3.2.3），一种将L-半乳糖酸-γ-内酯转化为ASC的酶。TBY-2原生质体的细胞分级分离表明，这种酶是专门定位于线粒体和相关的膜组分。在TBY-2细胞培养的生长周期中，GLDH呈一过性升高，在培养第3天达到最大值，此时正值对数生长期开始，细胞增殖活性也较高。ASC和GSH含量也观察到类似的行为。1.8.5.1坏血酸过氧化物酶（APX）、抗坏血酸自由基还原酶（AFRR）、脱氢抗坏血酸还原酶（达尔）和谷胱甘肽还原酶（GR）的活性也有一过性升高。1.6.4.2 1.6.5.4 1.11.1.11然而，增加的规模变化为APX和AFRR的约4倍，达尔的2倍和GR的11倍以上。ASC和GSH再循环酶的行为允许TBY-2细胞保持脱氢抗坏血酸和谷胱甘肽二硫化物在低水平，即使在高ASC和GSH利用的条件下。本文还讨论了TBY-2细胞悬浮培养生长周期中ASC和GSH代谢的关系。(C)2000年，Elsevier SAS科学与医学版。
The ascorbate (ASC) and glutathione (GSH) metabolisms were studied in cultured Nicotiana tabacum cv. Bright Yellow 2 (TBY-2) cells. TBY-2 cells were found to be endowed with L-galactono-gamma-lactone dehydrogenase (GLDH) (EC 1.3.2.3) an enzyme that converts L-galactono-gamma-lactone into ASC. Cellular fractionation of TBY-2 protoplasts indicated that this enzyme is exclusively localised in mitochondria and associated to the membrane fractions. During the growth cycle of TBY-2 cell culture, GLDH transiently increased, reaching the maximum value on the third day of culture, at the beginning of the exponential phase, when the cell proliferative activity was also higher. Similar behaviour has been observed for ASC and GSH contents. The activities of ascorbate peroxidase (APX) (EC 1.11.1.11), ascorbate-free radical reductase (AFRR) (EC 1.6.5.4), dehydroascorbic acid reductase (DHAR) (EC 1.8.5.1) and glutathione reductase (GR) (EC 1.6.4.2) also transiently raised. However, the scale of the increases varied being about 4-fold for APX and AFRR, 2-fold for DHAR and more than 11-fold for GR. The behaviour of the ASC and GSH recycling enzymes allowed TBY-2 cells to maintain both dehydroascorbic acid and glutathione disulphide at low levels, even under conditions of high ASC and GSH utilisation. The relationship between the ASC and GSH metabolisms during the growth cycle of TBY-2 cell suspension cultures is also discussed. (C) 2000 Editions scientifiques et medicales Elsevier SAS.