Rigaud J L, Leblanc G
Eur J Biochem. 1980 Sep;110(1):77-84. doi: 10.1111/j.1432-1033.1980.tb04842.x.
Cells of Mycoplasma mycoides var. Capri grown in a medium containing 10 micrograms/ml cholesterol (native organisms) or in cholesterol-free medium (adapted organisms) were treated with phospholipase A2. Hydrolysis of polar lipids (phosphatidylglycerol and diphosphatidylglycerol) only occurred in the adapted cells. Cholesterol replenishment of the membranes of these adapted cells in vitro which involves an increase from 7 micrograms to 66 micrograms cholesterol/mg membrane protein, completely abolished hydrolysis of polar lipid pools by phospholipase A2. This suggests that cholesterol incorporated either during growth or under conditions in vitro has an identical disposition and function in the membrane. This observation further indicates that cholesterol incorporation in M. mycoides var. Capri can be explained in terms of a simple physical adsorption process. Polar-lipid breakdown products resulting from phospholipase A2 action on intact cells, isolated membranes and lipids extracted from adapted organisms were analyzed. In experiments with intact cells [14C]oleic lysoderivatives but not [3H]palmitic lysoderivatives are accumulated within the membranes. In membrane preparations, again only [14C]oleic lysoderivatives are accumulated but transiently. Finally, both [14C]oleic and [3H]palmitic lysoderivatives were produced in phosphatidylglycerol-diphosphatidylglycerol liposomal preparations. From these results it can be concluded that: (a) 80% of the phosphatidylglycerol and diphosphatidylglycerol have an unusual positional distribution of their fatty acid (unsaturated oleic acid in position 1) and (b) membranes of M. mycoides var. Capri contain an active lysophospholipase which more efficiently hydrolyzes palmitic-acid-containing lysoderivatives.
将生长在含有10微克/毫升胆固醇的培养基中的丝状支原体山羊亚种细胞（天然生物体）或生长在无胆固醇培养基中的细胞（适应生物体）用磷脂酶A2处理。极性脂质（磷脂酰甘油和二磷脂酰甘油）的水解仅发生在适应细胞中。这些适应细胞的膜在体外补充胆固醇（膜蛋白中胆固醇含量从7微克增加到66微克/毫克）后，磷脂酶A2对极性脂质池的水解作用完全消失。这表明在生长过程中或体外条件下掺入的胆固醇在膜中具有相同的分布和功能。该观察结果进一步表明，丝状支原体山羊亚种中胆固醇的掺入可以用简单的物理吸附过程来解释。分析了磷脂酶A2作用于完整细胞、分离的膜和从适应生物体中提取的脂质所产生的极性脂质分解产物。在完整细胞的实验中，[14C]油酸溶血衍生物而非[3H]棕榈酸溶血衍生物在膜内积累。在膜制剂中，同样只有[14C]油酸溶血衍生物积累，但只是短暂积累。最后，在磷脂酰甘油 - 二磷脂酰甘油脂质体制剂中产生了[14C]油酸和[3H]棕榈酸溶血衍生物。从这些结果可以得出结论：（a）80%的磷脂酰甘油和二磷脂酰甘油的脂肪酸具有不寻常的位置分布（1位为不饱和油酸），并且（b）丝状支原体山羊亚种的膜含有一种活性溶血磷脂酶，其更有效地水解含棕榈酸的溶血衍生物。
