Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824.
Proc Natl Acad Sci U S A. 1989 Aug;86(15):5830-3. doi: 10.1073/pnas.86.15.5830.
Three classes of mutants of Arabidopsis thaliana (L.) Heynhold with alterations in starch metabolism were found to have higher levels of leaf amylase activity than the wild type when grown in a 12-hr photoperiod. This effect was dependent upon the developmental stage of the plants and was largely suppressed during growth in continuous light. The various amylolytic activities in crude extracts were separated by electrophoresis in nondenaturing polyacrylamide gels and visualized by activity staining. The increased amylase activity in the mutants was due to an up to 40-fold increase in the activity of an extrachloroplast beta-amylase (EC 3.2.1.2). These observations indicate the existence of a regulatory mechanism that controls the amount of beta-amylase activity in response to fluctuations in photosynthetic carbohydrate metabolism. It is paradoxical that beta-amylase appears to be a highly regulated enzyme, but as yet no physiologically relevant function can be assigned to this enzyme due to the absence of starch in the cytoplasmic compartment of leaf cells.
在 12 小时光周期下生长时，发现拟南芥（L.）Heynhold 的三种淀粉代谢改变的突变体的叶片淀粉酶活性比野生型高。这种效应依赖于植物的发育阶段，并且在连续光照下生长时，大部分受到抑制。在非变性聚丙烯酰胺凝胶中通过电泳分离粗提物中的各种淀粉水解酶，并通过活性染色进行可视化。突变体中增加的淀粉酶活性是由于叶绿体外的β-淀粉酶（EC 3.2.1.2）活性增加了 40 倍。这些观察结果表明存在一种调节机制，该机制可根据光合作用碳水化合物代谢的波动来控制β-淀粉酶活性的量。β-淀粉酶似乎是一种高度调控的酶，但由于细胞质隔室中不存在淀粉，因此尚未能赋予该酶任何生理相关的功能，这是矛盾的。
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