植物中淀粉的代谢及其调控研究进展

Research Progress of Starch Metabolism and its Regulation in Plants

在植物淀粉的合成和降解过程中,主要涉及ADPG焦磷酸化酶、淀粉合成酶、淀粉分支酶、淀粉去分支酶以及淀粉磷酸化酶和淀粉水解酶,它们在淀粉代谢中分别发挥着不同作用。ADPG焦磷酸化酶催化葡萄糖-1-磷酸形成腺苷二磷酸葡萄糖(ADPG),起始淀粉的合成;淀粉合成酶将ADPG的葡聚糖基转移到α-1,4-葡萄糖的非还原性末端;分支酶在直链淀粉上形成α-1,6分支点;去分支酶与分支酶的作用相反;淀粉水解酶和磷酸化酶主要将淀粉降解为葡萄糖单体。近年来,人们对这些酶的结构、特性、功能及表达调控等方面的研究已取得了重要进展。在此,本文对上述各种核心酶的同工酶形式、生化特性和功能的研究进展进行了综述,并讨论了淀粉代谢中的调控方式,包括酶的别构效应,氧化还原作用,蛋白磷酸化以及形成多酶复合体。同时,展望了今后淀粉代谢的研究前景。

In the case of starch metabolism in plant, the major enzymes comprising the synthetic and degradative pathways are ADP-Glc pyrophosphorylase, which synthesizes ADPG as sugar nucleotide precursors; starch synthase, which extends α-1,4 linked glucan chains using ADPG; starch-branching enzymes, which introduces α-1,6 branch points; starch debranching enzymes, which hydrolyze α-1,6 branches in glucans; starch phosphorylase and a series of hydrolytic enzymes, both of which are responsible for degradation of linear glucan chains to glucosyl monomers. By analyzing the structure, properties, functions and regulations of expression of these enzymes, a lot of achievement have been made. In this paper, recent advances in biochemical characterizations and different isoform concerning these enzymes were reviwed, and the regulation of the starch metabolic pathways including allosteric modulation by metabolites; redox modulation; protein phosphorylation and the formation of protein complexes were also particularly discussed. At last, this article discussed the research foreground of starch metabolism in plant.