Department of Cell and Molecular Biology of Drugs, Faculty of Pharmacy, Comenius University, Bratislava, Slovakia.
Phytochemistry. 2011 Feb;72(2-3):160-5. doi: 10.1016/j.phytochem.2010.11.020. Epub 2010 Dec 18.
Plant phospholipases D (PLDs) occur in a large variety of isoenzymes, which differ in Ca(2+) ion requirement, phosphatidylinositol-4,5-bisphosphate (PIP(2)) activation and substrate selectivity. In the present study a membrane-bound PLD has been identified in the microsomal fractions of poppy seedlings (Papaver somniferum). The maximum PLD activity is found after 2 days of germination in endosperms and after 3 days in developing seedlings. In contrast to the four poppy PLD isoenzymes described hitherto, the membrane-bound form is active at lower Ca(2+) ion concentrations (in the micromolar instead of millimolar range) and needs PIP(2) for hydrolytic activity. Remarkable differences are also observed in head group exchange reactions. The reaction rates of the transphosphatidylation of phosphatidylcholine by various acceptor alcohols follow the sequence glycerol>serine>myo-inositol>ethanolamine, whereas ethanolamine is preferred by most other PLDs. Despite the biocatalytic differences, the membrane-bound PLD interacts with polyclonal antibodies raised against α-type PLD, which reveals some structural similarities between these two enzymes.
植物磷酯酶 D（PLD）存在于多种同工酶中，这些同工酶在钙离子需求、磷脂酰肌醇-4,5-二磷酸（PIP（2））激活和底物选择性方面存在差异。本研究在罂粟幼苗（Papaver somniferum）的微粒体部分中鉴定出一种膜结合的 PLD。在胚乳中，最大的 PLD 活性在发芽后 2 天出现，在发育中的幼苗中在 3 天后出现。与迄今为止描述的四种罂粟 PLD 同工酶不同，膜结合形式在较低的钙离子浓度（微摩尔而不是毫摩尔范围）下具有活性，并需要 PIP（2）才能进行水解活性。在头基交换反应中也观察到显著差异。各种受体醇通过转磷酸化反应对卵磷脂的反应速率遵循甘油>丝氨酸>肌醇>乙醇胺的顺序，而大多数其他 PLD 则更喜欢乙醇胺。尽管存在生物催化差异，但膜结合的 PLD 与针对 α 型 PLD 产生的多克隆抗体相互作用，这表明这两种酶之间存在一些结构相似性。
