Gemel J, Kaniuga Z
Eur J Biochem. 1987 Jul 1;166(1):229-33. doi: 10.1111/j.1432-1033.1987.tb13506.x.
Galactolipase activity in chloroplasts of several chill-resistant plants was found to be very low [0.02-0.13 mumol free fatty acid (FFA) liberated min-1 mg protein-1] or not detected. The same phenomenon was observed for soybean and members of the Cucurbitaceae such as cucumber, pumpkin, melon and squash. Since, following cold storage of cucumber leaves, the levels of monogalactosyl-diacylglycerol and digalactosyl-diacylglycerol in chloroplasts decrease while those of FFA accumulate it seems likely that in these typical chill-sensitive plants galactolipase is present but inactivated during isolation procedure. The low galactolipase activity in chloroplasts was accompanied by a relatively low FFA content ranging from 0.05 mumol to 0.30 mumol FFA mg chlorophyll (Chl)-1. However, both pea and horse bean chloroplasts (with low galactolipase activity) exhibit about 0.45 mumol FFA mg Chl-1. Elevated galactolipase activity was observed in chloroplasts of most chill-sensitive species (ranging from 0.31 mumol to 1.32 mumol FFA liberated min-1 mg protein-1) as well as in chloroplasts from broad bean, a member of a chill-resistant species (1.26 mumol FFA liberated min-1 mg protein-1). In addition in this latter group of plants FFA level in chloroplasts often did not fit the galactolipase activity. The results suggest that there exists a tendency for chilling tolerance of plants to decrease both galactolipase activity and FFA level. However, in some plant species with elevated galactolipase activity the chloroplast FFA level does not correlate with enzyme activity.
在几种抗寒植物的叶绿体中，半乳糖脂酶活性被发现非常低[0.02 - 0.13微摩尔游离脂肪酸（FFA）每分钟释放量毫克蛋白-1]或未检测到。大豆以及葫芦科植物如黄瓜、南瓜、甜瓜和西葫芦也观察到同样的现象。由于黄瓜叶片冷藏后，叶绿体中单半乳糖基二酰基甘油和双半乳糖基二酰基甘油的水平降低，而FFA水平积累，似乎在这些典型的冷敏感植物中，半乳糖脂酶是存在的，但在分离过程中失活了。叶绿体中低水平的半乳糖脂酶活性伴随着相对较低的FFA含量，范围从0.05微摩尔到0.30微摩尔FFA毫克叶绿素（Chl）-1。然而，豌豆和蚕豆的叶绿体（半乳糖脂酶活性低）都表现出约0.45微摩尔FFA毫克Chl-1。在大多数冷敏感物种的叶绿体中观察到半乳糖脂酶活性升高（范围从0.31微摩尔到1.32微摩尔FFA每分钟释放量毫克蛋白-1），以及在抗寒物种蚕豆的叶绿体中（1.26微摩尔FFA每分钟释放量毫克蛋白-1）。此外，在这后一组植物中，叶绿体中的FFA水平常常与半乳糖脂酶活性不匹配。结果表明，植物的抗寒能力存在一种降低半乳糖脂酶活性和FFA水平的趋势。然而，在一些半乳糖脂酶活性升高的植物物种中，叶绿体FFA水平与酶活性不相关。
