Vieweg G H, de Fekete M A
Fachbereich Biologie der Technischen Hochschule, Schnittspahnstraße 3, D-6100, Darmstadt, Federal Republik of Germany.
Planta. 1976 Jan;129(2):155-9. doi: 10.1007/BF00390022.
The presence of phospholipids reduces the breakdown of amylose catalyzed by β-amylase, phosphorylase and α-amylase. The activities of the β-amylases of sweet potato (Ipomoea batatas) and barley (Hordeum vulgare L.) disminish to less than 10% of the activity in the control without the phospholipids. When the amylose was complexed with phospholipids the activity of the α-amylase of Bacillus subtilis was reduced to about 25% of the control value. A similar effect was observed for the amylases of Zea mays leaves. The phosphorylase effected almost no phosphorolysis of the complexed amylose, but starch synthesis from glucose-1-phosphate proceeded at a rate that was about 60% of that with pure amylose. The activity of the synthetase from bundle sheath cells of maize leaves was not influenced much by the presence of phospholipids, whereas the "branching enzyme" of maize endosperm did not produce any amylopectin from the complexed amylose. -These facts could explain the simultaneous deposition of amylose and amylopectin in the starch granules. Some of the newly formed glucan chains may be protected by formation of a complex with the phospholipids. This protected amylose can not undergo branching or breakdown, but it can be elongated owing to the activity of synthetase or phosphorylase. Amylopectin is formed from the chains that are not complexed.
磷脂的存在会减少由β-淀粉酶、磷酸化酶和α-淀粉酶催化的直链淀粉的分解。甘薯（Ipomoea batatas）和大麦（Hordeum vulgare L.）的β-淀粉酶活性降低至无磷脂对照中活性的不到10%。当直链淀粉与磷脂复合时，枯草芽孢杆菌α-淀粉酶的活性降低至对照值的约25%。玉米叶片的淀粉酶也观察到类似效果。磷酸化酶对复合直链淀粉几乎不产生磷酸解作用，但由葡萄糖-1-磷酸合成淀粉的速率约为纯直链淀粉的60%。玉米叶片维管束鞘细胞合成酶的活性受磷脂存在的影响不大，而玉米胚乳的“分支酶”不能从复合直链淀粉产生任何支链淀粉。——这些事实可以解释直链淀粉和支链淀粉在淀粉颗粒中的同时沉积。一些新形成的葡聚糖链可能通过与磷脂形成复合物而受到保护。这种受保护的直链淀粉不能进行分支或分解，但由于合成酶或磷酸化酶的活性可以延长。支链淀粉由未复合的链形成。
