Mahadevappa V G, Holub B J
J Biol Chem. 1983 May 10;258(9):5337-9.
The relative degradation of the various molecular species of phosphatidylinositol in response to thrombin was studied in human platelets. For this purpose, platelets were prelabeled with [2-3H]glycerol and the loss of radioactivity from the saturated, monoenoic, dienoic, trienoic, tetraenoic, and greater than tetraenoic [3H]phosphatidylinositols was determined after conversion to their 1,2-diacylglycerol acetate derivatives and fractionation by argentation thin layer chromatography. Within 90 s, when the thrombin-dependent degradation of total [3H] phosphatidylinositol amounted to 49.5%, the percentage loss of radioactivity from the tetraenoic (1-stearoyl 2-arachidonoyl) species and greater than tetraenes was significantly greater than that for the other molecular classes and approximately twice that for the monoenes. Furthermore, the extent of degradation tended to decrease with decreasing unsaturation of the phosphatidylinositols in intact platelets. These results indicate that the thrombin-dependent hydrolysis of phosphatidylinositol in intact human platelets exhibits a preferential degradation of 1-acyl (predominantly stearoyl plus oleoyl) 2-arachidonoyl species relative to other molecular species which may possibly be of importance in platelet aggregation.
在人血小板中研究了磷脂酰肌醇的各种分子种类对凝血酶的相对降解情况。为此，用[2-³H]甘油对血小板进行预标记，在将饱和、单烯、二烯、三烯、四烯及大于四烯的[³H]磷脂酰肌醇转化为其1,2-二酰基甘油乙酸酯衍生物并通过银化薄层层析分离后，测定放射性的损失。在90秒内，当总[³H]磷脂酰肌醇的凝血酶依赖性降解达到49.5%时，四烯（1-硬脂酰2-花生四烯酰）种类及大于四烯的放射性损失百分比显著高于其他分子类别，约为单烯的两倍。此外，在完整血小板中，磷脂酰肌醇的不饱和程度降低时，降解程度趋于下降。这些结果表明，完整人血小板中磷脂酰肌醇的凝血酶依赖性水解相对于其他分子种类表现出1-酰基（主要是硬脂酰加油酰）2-花生四烯酰种类的优先降解，这可能在血小板聚集中具有重要意义。
