Muga A, Arrondo J L, Gurtubay J I, Goñi F M
Department of Biochemistry, University of Basque Country, Bilbao, Spain.
J Biol Chem. 1990 Apr 15;265(11):5956-9.
When the major polar lipid of purple membrane, a dialkyl analogue of phosphatidyl glycerophosphate, is treated with phospholipase D under the usual assay conditions for this enzyme, the reaction yields dialkylglycerol and glycerol bisphosphate, i.e. the kind of products that would be expected from a phospholipase C reaction. The effect is seen both in native purple membranes and with the pure phospholipid in the form of liposomes. The specific activity and kinetic parameters Km and Vmax of phospholipase D for the purple membrane phospholipid are similar to those for egg phosphatidylcholine. The presence of phospholipase C impurities in the phospholipase D preparations has been ruled out as an explanation for the above observations. A hypothesis is suggested, taking into account the peculiar headgroup structure of the bacterial lipid, to explain the seemingly anomalous enzyme behavior.
当紫膜的主要极性脂质（磷脂酰甘油磷酸的二烷基类似物）在该酶的常规测定条件下用磷脂酶D处理时，反应产生二烷基甘油和甘油二磷酸，即磷脂酶C反应预期产生的那种产物。在天然紫膜和脂质体形式的纯磷脂中都能观察到这种效应。磷脂酶D对紫膜磷脂的比活性以及动力学参数Km和Vmax与对鸡蛋磷脂酰胆碱的相似。已经排除了磷脂酶D制剂中存在磷脂酶C杂质作为上述观察结果的解释。考虑到细菌脂质独特的头部基团结构，提出了一个假说来解释这种看似异常的酶行为。
