Acyl chain specificity and kinetic properties of phospholipase A1 and A2 of bone marrow-derived macrophages.

Zeitschrift fur Naturforschung. Section C, Biosciences Pub Date : 1985-05-01 DOI:10.1515/znc-1985-5-613

I Flesch, B Schmidt, E Ferber

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引用次数: 19

Abstract

The fatty acyl specificity of phospholipase A1 and A2 in homogenates of mouse bone marrow-derived macrophages was determined using phosphatidylcholine and phosphatidylethanolamine of different acyl chain composition. Phosphatidylcholine with arachidonoyl at position 2 was cleaved preferentially by an alkaline phospholipase A2 (pH-optimum 9.0) leading to selective liberation of arachidonic acid. In contrast, phosphatidylcholines with oleoyl or linoleoyl at position 2 were degraded mainly by an acid phospholipase A1 (pH-optimum 4-5) resulting in a conservation of these fatty acids esterified in lysophosphatides. Substrate kinetics of the alkaline phospholipase A2 revealed a 30 fold higher affinity (Km = 3.8 X 10(-7) M) for 1-acyl-2-arachidonoyl-glycerophosphocholine compared to 1-acyl-2-oleoyl-glycerophosphocholine. The kinetic data were not influenced by endogenous lipids indicating that exogenous substrates do not equilibrate with cellular lipids. These results are suitable to explain a selective liberation of arachidonic acid from a mixture of phospholipids.

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骨髓源性巨噬细胞磷脂酶A1和A2的酰基链特异性和动力学性质。

采用不同酰基链组成的磷脂酰胆碱和磷脂酰乙醇胺测定小鼠骨髓源性巨噬细胞匀浆中磷脂酶A1和A2的脂肪酰基特异性。碱性磷脂酶A2 (ph最适9.0)优先裂解位于2位的花生四烯酰基磷脂胆碱，导致花生四烯酸选择性释放。相反，2位油基或亚油基的磷脂酰胆碱主要被酸性磷脂酶A1 (ph值最优的4-5)降解，导致这些脂肪酸在溶血磷脂中被酯化。碱性磷脂酶A2的底物动力学表明，与1-酰基-2-花生四烯酰基-甘油酰胆碱相比，1-酰基-2-油基-甘油酰胆碱的亲和力高30倍(Km = 3.8 X 10(-7) M)。动力学数据不受内源性脂质影响，表明外源性底物不与细胞脂质平衡。这些结果适用于解释花生四烯酸从磷脂混合物中选择性释放。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Zeitschrift fur Naturforschung. Section C, Biosciences

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