Bohn Lisbeth, Meyer Anne S, Rasmussen Søren K
Department of Agricultural Sciences, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark.
J Zhejiang Univ Sci B. 2008 Mar;9(3):165-91. doi: 10.1631/jzus.B0710640.
Phytic acid (PA) is the primary storage compound of phosphorus in seeds accounting for up to 80% of the total seed phosphorus and contributing as much as 1.5% to the seed dry weight. The negatively charged phosphate in PA strongly binds to metallic cations of Ca, Fe, K, Mg, Mn and Zn making them insoluble and thus unavailable as nutritional factors. Phytate mainly accumulates in protein storage vacuoles as globoids, predominantly located in the aleurone layer (wheat, barley and rice) or in the embryo (maize). During germination, phytate is hydrolysed by endogenous phytase(s) and other phosphatases to release phosphate, inositol and micronutrients to support the emerging seedling. PA and its derivatives are also implicated in RNA export, DNA repair, signalling, endocytosis and cell vesicular trafficking. Our recent studies on purification of phytate globoids, their mineral composition and dephytinization by wheat phytase will be discussed. Biochemical data for purified and characterized phytases isolated from more than 23 plant species are presented, the dephosphorylation pathways of phytic acid by different classes of phytases are compared, and the application of phytase in food and feed is discussed.
植酸（PA）是种子中磷的主要储存化合物，占种子总磷量的80%，占种子干重的1.5%。PA中带负电荷的磷酸盐与钙、铁、钾、镁、锰和锌等金属阳离子强烈结合，使其不溶，因此无法作为营养因子利用。植酸盐主要以球状体的形式积累在蛋白质储存液泡中，主要位于糊粉层（小麦、大麦和水稻）或胚中（玉米）。在萌发过程中，植酸被内源性植酸酶和其他磷酸酶水解，释放出磷酸盐、肌醇和微量营养素，以支持新出现的幼苗。PA及其衍生物还与RNA输出、DNA修复、信号传导、内吞作用和细胞囊泡运输有关。我们将讨论最近关于植酸球状体的纯化、其矿物质组成以及小麦植酸酶脱植酸作用的研究。给出了从23种以上植物物种中分离得到的纯化和表征的植酸酶的生化数据，比较了不同类别的植酸酶对植酸的去磷酸化途径，并讨论了植酸酶在食品和饲料中的应用。
