Wolosiuk R A, Buchanan B B
Department of Cell Physiology, University of California, Berkeley, California 94720.
Plant Physiol. 1978 Apr;61(4):669-71. doi: 10.1104/pp.61.4.669.
NADP-glyceraldehyde-3-P dehydrogenase of spinach (Spinacia oleracea) chloroplasts was activated by thioredoxin that was reduced either photochemically with ferredoxin and ferredoxin-thioredoxin reductase or chemically with dithiothreitol. The activation process that was observed with the soluble protein fraction from chloroplasts and with the purified regulatory form of the enzyme was slow relative to the rate of catalysis. The NAD-linked glyceraldehyde-3-P dehydrogenase activity that is also present in chloroplasts and in the purified enzyme preparation was not affected by reduced thioredoxin.When activated by dithiothreitol-reduced thioredoxin, the regulatory form of NADP-glyceraldehyde-3-P dehydrogenase was partly deactivated by oxidized glutathione. The enzyme activated by photochemically reduced thioredoxin was not appreciably affected by oxidized glutathione. The results suggest that although it resembles other regulatory enzymes in its requirements for light-dependent activation by the ferredoxin/thioredoxin system, NADP-glyceraldehyde-3-P dehydrogenase differs in its mode of deactivation and in its capacity for activation by enzyme effectors independently of thioredoxin.
菠菜（Spinacia oleracea）叶绿体中的NADP - 甘油醛-3-磷酸脱氢酶可被硫氧还蛋白激活，硫氧还蛋白可通过铁氧化还原蛋白和铁氧化还原蛋白-硫氧还蛋白还原酶进行光化学还原，也可通过二硫苏糖醇进行化学还原。相对于催化速率而言，在叶绿体的可溶性蛋白组分以及该酶的纯化调节形式中观察到的激活过程较为缓慢。叶绿体和纯化酶制剂中也存在的NAD连接的甘油醛-3-磷酸脱氢酶活性不受还原型硫氧还蛋白的影响。当被二硫苏糖醇还原的硫氧还蛋白激活时，NADP - 甘油醛-3-磷酸脱氢酶的调节形式会被氧化型谷胱甘肽部分失活。被光化学还原的硫氧还蛋白激活的酶不受氧化型谷胱甘肽的明显影响。结果表明，尽管NADP - 甘油醛-3-磷酸脱氢酶在依赖铁氧化还原蛋白/硫氧还蛋白系统进行光依赖性激活的需求方面类似于其他调节酶，但其失活模式以及独立于硫氧还蛋白被酶效应物激活的能力有所不同。
