Collins P D, Hague D R
J Biol Chem. 1983 Mar 25;258(6):4012-8.
Illumination of etiolated maize plants for 80 h brings about a 15-20-fold increase in activity of NADP malic enzyme (EC 1.1.1.40). Increases in NADP malic enzyme protein and in the level of translatable mRNA for this protein occur simultaneously with the activity increase. Radiolabeled amino acids are also incorporated into NADP malic enzyme during this time. These results are consistent with the conclusion that an increase in NADP malic enzyme activity during greening results from de novo synthesis of NADP malic enzyme protein. Polyadenylated RNA extracted from greening maize leaves directs the synthesis in vitro of a protein 12,000 daltons larger than NADP malic enzyme purified from corn leaves. This protein is a precursor of NADP malic enzyme because 1) both the precursor and mature NADP malic enzyme are immunoprecipitated by antibody made against NADP malic enzyme purified from corn leaves, 2) both NADP malic enzyme protein and the level of mRNA for the precursor increase during greening, and 3) peptide maps of the precursor and of mature NADP malic enzyme are very similar. Mature NADP malic enzyme and its precursor (synthesized in vitro) both migrate on sodium dodecyl sulfate-polyacrylamide gradient gels as doublet bands. Peptide analyses show all bands to be structurally related.
将黄化玉米植株光照80小时会使NADP苹果酸酶（EC 1.1.1.40）的活性提高15至20倍。NADP苹果酸酶蛋白及其可翻译mRNA水平的增加与活性增加同时发生。在此期间，放射性标记的氨基酸也会掺入NADP苹果酸酶中。这些结果与以下结论一致，即绿化过程中NADP苹果酸酶活性的增加是由于NADP苹果酸酶蛋白的从头合成。从绿化玉米叶片中提取的聚腺苷酸化RNA在体外指导合成一种比从玉米叶片中纯化的NADP苹果酸酶大12,000道尔顿的蛋白质。这种蛋白质是NADP苹果酸酶的前体，因为：1）前体和成熟的NADP苹果酸酶都能被针对从玉米叶片中纯化的NADP苹果酸酶制备的抗体免疫沉淀；2）在绿化过程中，NADP苹果酸酶蛋白和前体的mRNA水平都增加；3）前体和成熟NADP苹果酸酶的肽图非常相似。成熟的NADP苹果酸酶及其前体（体外合成）在十二烷基硫酸钠-聚丙烯酰胺梯度凝胶上均迁移为双峰带。肽分析表明所有条带在结构上相关。
