Goldfischer S, Johnson A B, Morecki R
Lab Invest. 1976 Jul;35(1):55-62.
Skeletal abnormalities with defective formation of mature calcified bone are the most prominent clinical features of hypophosphatasia. Low concentrations of serum and tissue alkaline phosphatase and elevated plasma and urinary levels of phosphorylethanolamine (PEA) are also present. Although PEA is hydrolyzed by serum alkaline phosphatase, the relationship between PEA and the deficiency is unclear. PEA has not previously been tested as a cytochemical substrate for the in situ demonstration of human alkaline phosphatase activity. We have studied alkaline phosphatase activity in hypophosphatasia in tissue sections, utilizing PEA and adenosinetriphosphate (ATP) as well as the usual beta-glycerophosphate and naphthol phosphate substrates. Neutral and acid phosphatase activities were also examined. Our results demonstrate that PEA is a substrate for the localization of alkaline phosphatase in normal human tissue, but is not hydrolyzed in hypophosphatasia in the liver, brain or costochondral junction under alkaline conditions. In the kidney in hypophosphatasia only the straight segments of proximal tubules that rim the medullary rays are reactive with PEA. Similar results in hypophosphatasia were obtained at an alkaline pH with ATP, beta-glycerophosphate, and naphthol phosphate. However, the defect in hypophosphatasia is not a generalized deficiency of membrane-associated phosphatases because membranes that were deficient in alkaline phosphatase activity demonstrated normal reactivity with ATP at neutral pH. In addition, thiamine pyrophosphate was also split by Golgi membranes within the cytoplasm. Acid hydrolysis of beta-glycerophosphate by lysosomes was normal.
成熟钙化骨形成缺陷的骨骼异常是低磷酸酯酶症最突出的临床特征。血清和组织碱性磷酸酶浓度降低，同时血浆和尿液中的磷酸乙醇胺（PEA）水平升高。尽管PEA可被血清碱性磷酸酶水解，但PEA与该缺乏症之间的关系尚不清楚。此前尚未将PEA作为细胞化学底物用于原位显示人碱性磷酸酶活性。我们利用PEA、三磷酸腺苷（ATP）以及常用的β-甘油磷酸酯和萘酚磷酸酯底物，研究了低磷酸酯酶症组织切片中的碱性磷酸酶活性。还检测了中性和酸性磷酸酶活性。我们的结果表明，PEA是正常人组织中碱性磷酸酶定位的底物，但在碱性条件下，在低磷酸酯酶症患者的肝脏、大脑或肋软骨连接处不被水解。在低磷酸酯酶症患者的肾脏中，只有环绕髓放线的近端小管直段与PEA有反应。在碱性pH条件下，使用ATP、β-甘油磷酸酯和萘酚磷酸酯在低磷酸酯酶症中也得到了类似结果。然而，低磷酸酯酶症中的缺陷并非膜相关磷酸酶的普遍缺乏，因为碱性磷酸酶活性缺乏的膜在中性pH条件下对ATP显示出正常反应性。此外，硫胺素焦磷酸也被细胞质内的高尔基膜分解。溶酶体对β-甘油磷酸酯的酸性水解正常。
