Department of Horticulture, The Pennsylvania State University, University Park, Pennsylvania 16802.
Plant Physiol. 1981 Mar;67(3):525-9. doi: 10.1104/pp.67.3.525.
Starch granules with associated metabolites were isolated from immature Zea mays L. endosperm by a nonaqueous procedure using glycerol and 3-chloro-1,2-propanediol. The soluble extract of the granule preparation contained varying amounts of neutral sugars, inorganic phosphate, hexose and triose phosphates, organic acids, adenosine and uridine nucleotides, sugar nucleotides, and amino acids. Based on the metabolites present and on information about translocators in chloroplast membranes, which function in transferring metabolites from the chloroplast stroma into the cytoplasm, it is suggested that sucrose is degraded in the cytoplasm, via glycolysis, to triose phosphates which cross the amyloplast membrane by means of a phosphate translocator. It is further postulated that hexose phosphates and sugars are produced from the triose phosphates in the amyloplast stroma by gluconeogenesis with starch being formed from glucose 1-phosphate via pyrophosphorylase and starch synthase enzymes. The glucose 1-phosphate to inorganic phosphate ratio in the granule preparation was such that starch synthesis by phosphorylase is highly unlikely in maize endosperm.
采用甘油和 3-氯-1,2-丙二醇的非水程序，从未成熟的玉米胚乳中分离出与代谢物相关的淀粉颗粒。颗粒制剂的可溶性提取物含有不同量的中性糖、无机磷酸盐、己糖和丙糖磷酸、有机酸、腺苷和尿苷核苷酸、糖核苷酸和氨基酸。基于存在的代谢物以及关于叶绿体膜中转运蛋白的信息，这些转运蛋白的功能是将代谢物从叶绿体基质转移到细胞质中，因此，推测蔗糖在细胞质中通过糖酵解降解为三磷酸丙糖，三磷酸丙糖通过磷酸转运蛋白穿过淀粉体膜。进一步推测，己糖磷酸和糖是由淀粉体基质中的三磷酸丙糖通过糖异生产生的，淀粉是通过焦磷酸化酶和淀粉合酶酶从葡萄糖 1-磷酸形成的。颗粒制剂中葡萄糖 1-磷酸与无机磷酸盐的比值表明，玉米胚乳中磷酸化酶的淀粉合成极不可能。
Zotero 插件