Scott J E, Oulton M, Boylan M R, Dolphin M, Fraser M O, Temple S
Biochim Biophys Acta. 1987 Sep 4;921(1):75-81. doi: 10.1016/0005-2760(87)90172-x.
Phospholipase A2 activity was determined in subcellular fractions and lamellar bodies of fetal, neonatal and adult rabbit lungs. Specific activity in most fractions decreased from the 24th to the 28th day of gestation. All fractions except the mitochondrial and the nuclear fractions exhibited a sharp increase in activity in the newborn lung. Specific activity in the adult lung generally declined in comparison to neonatal values. During gestation total enzyme activity per gram of lung was concentrated in the cytosolic fraction. With the exception of the lamellar body fraction, the total content of phospholipase A2 activity increased dramatically in all fractions from the neonatal lung. The lamellar body fractions displayed both low specific activity and low total enzyme activity during gestation. Specific activity increased dramatically in the neonatal and adult lung but still accounted for only a small fraction of the activity in comparison to the other subcellular fractions. The subcellular content of disaturated phosphatidylcholine (PC) appeared to correlate well with the activity of phospholipase A2 in the neonatal mitochondrial, microsomal and cytosolic fractions. Since decreasing prenatal enzyme levels are associated with increasing disaturated PC content, the alkaline and calcium-dependent phospholipase A2 may not be directly involved in disaturated PC synthesis in the fetus. However, postnatally, the correlation between the pattern of production of disaturated PC and the activity of the phospholipase A2 indicates a role for this enzyme in surfactant-related disaturated PC synthesis.
在胎儿、新生儿和成年兔肺的亚细胞组分和板层小体中测定了磷脂酶A2活性。大多数组分中的比活性在妊娠第24天至第28天期间下降。除线粒体和核组分外，所有组分在新生肺中的活性均急剧增加。与新生儿的值相比，成年肺中的比活性普遍下降。在妊娠期间，每克肺的总酶活性集中在胞质组分中。除板层小体组分外，新生儿肺中所有组分的磷脂酶A2活性总含量均显著增加。板层小体组分在妊娠期间表现出低比活性和低总酶活性。比活性在新生儿和成年肺中显著增加，但与其他亚细胞组分相比，仍仅占活性的一小部分。在新生儿的线粒体、微粒体和胞质组分中，二饱和磷脂酰胆碱（PC）的亚细胞含量似乎与磷脂酶A2的活性密切相关。由于产前酶水平的降低与二饱和PC含量的增加有关，碱性和钙依赖性磷脂酶A2可能不直接参与胎儿中二饱和PC的合成。然而，出生后，二饱和PC的产生模式与磷脂酶A2活性之间的相关性表明该酶在与表面活性剂相关的二饱和PC合成中起作用。
