Dippe Martin, Ulbrich-Hofmann Renate
Institute of Biochemistry and Biotechnology, Martin-Luther University, Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06099 Halle, Germany.
Phytochemistry. 2009 Feb;70(3):361-5. doi: 10.1016/j.phytochem.2009.01.011. Epub 2009 Feb 27.
Phospholipase D (PLD) catalyzes the hydrolysis and transesterification of glycerophospholipids at the terminal phosphodiester bond. In many plants, several isoforms of PLD have been identified without knowing their functional differences. In this paper, the specificities of two PLD isoenzymes from white cabbage (Brassica oleracea var. capitata) and two ones from opium poppy (Papaver somniferum L.), which were recombinantly produced in Escherichia coli, were compared in the hydrolysis of phospholipids with different head groups and in the transphosphatidylation of phosphatiylcholine with several acceptor alcohols. In a biphasic reaction system, consisting of buffer and diethyl ether, the highly homologous isoenzymes are able to hydrolyze phosphatidylcholine, -glycerol, -ethanolamine, -inositol and - with one exception - also phosphatidylserine but with different individual reaction rates. In transphosphatidylation of phosphatidylcholine, they show significant differences in the rates of head group exchange but with the same trend in the preference of acceptor alcohols (ethanolamine>glycerol>>l-serine). For l- and d-serine a stereoselectivity of PLD was observed. The results suggest a physiological relevance of the different hydrolytic and transphosphatidylation activities in plant PLD isoenzymes.
磷脂酶D（PLD）催化甘油磷脂在末端磷酸二酯键处的水解和转酯反应。在许多植物中，已鉴定出几种PLD同工型，但尚不清楚它们的功能差异。本文比较了在大肠杆菌中重组产生的来自白菜（Brassica oleracea var. capitata）的两种PLD同工酶和来自罂粟（Papaver somniferum L.）的两种PLD同工酶在水解具有不同头部基团的磷脂以及用几种受体醇对磷脂酰胆碱进行转磷脂酰基反应中的特异性。在由缓冲液和二乙醚组成的双相反应体系中，高度同源的同工酶能够水解磷脂酰胆碱、磷脂酰甘油、磷脂酰乙醇胺、磷脂酰肌醇，并且除了一个例外，还能水解磷脂酰丝氨酸，但各自的反应速率不同。在磷脂酰胆碱的转磷脂酰基反应中，它们在头部基团交换速率上表现出显著差异，但在受体醇的偏好上具有相同的趋势（乙醇胺>甘油>>L-丝氨酸）。对于L-丝氨酸和D-丝氨酸，观察到了PLD的立体选择性。结果表明植物PLD同工酶中不同的水解和转磷脂酰基活性具有生理相关性。
