The only known compositional change in the phospholipids (PL) of pulmonary surfactant in response to a physiologic stimulus occurs around the time of birth. In most species, the predominant anionic PL changes from phosphatidylinositol (PtdIns) to phosphatidylglycerol (PtdGro). Because prior studies have shown that the change in the headgroup itself is functionally insignificant, we tested the hypothesis that the PtdIns and PtdGro contain different diacyl pairs. Experiments used electrospray‐ionization mass spectrometry to determine the molecular species in PtdIns, PtdGro, and phosphatidylcholine (PtdCho) in surfactant from newborn calves and cows. The profiles for the two anionic PL were distinct. The PtdIns contained long, unsaturated fatty acid chains and no disaturated species. The PtdGro more closely resembled the profile from PtdCho. For each headgroup, the molecular species for calf and cow were similar. The differences between the two anionic PL indicate that the switch from PtdIns to PtdGro during maturation involves more than simple substitution of the headgroup, and suggest that the functional significance of the shift may reflect the different pool of diacyl pairs.

中文翻译：

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牛肺表面活性剂的阴离子磷脂。

响应生理刺激，肺表面活性物质的磷脂 (PL) 唯一已知的成分变化发生在出生前后。在大多数物种中，主要的阴离子 PL 从磷脂酰肌醇 (PtdIns) 变为磷脂酰甘油 (PtdGro)。由于先前的研究表明头组本身的变化在功能上无关紧要，我们测试了 PtdIns 和 PtdGro 包含不同二酰基对的假设。实验使用电喷雾电离质谱法来确定新生小牛和奶牛表面活性剂中 PtdIns、PtdGro 和磷脂酰胆碱 (PtdCho) 的分子种类。两种阴离子 PL 的分布是不同的。PtdIns 含有长的不饱和脂肪酸链，没有不饱和物质。PtdGro 更类似于来自 PtdCho 的配置文件。对于每个头组，小牛和母牛的分子种类相似。两种阴离子 PL 之间的差异表明，成熟过程中从 PtdIns 到 PtdGro 的转换涉及的不仅仅是头基的简单替换，并且表明这种转变的功能意义可能反映了不同的二酰基对池。