Matsushita M, Irino T, Minowa M, Komoda T, Stigbrand T
Department of Medical Biochemistry and Biophysics, University of Umeå, Sweden.
Ann Clin Biochem. 1998 Jul;35 ( Pt 4):515-21. doi: 10.1177/000456329803500405.
We examined the appearance of high-molecular-mass placental alkaline phosphatases (HPLAPs) in the serum of normal pregnant women by means of polyacrylamide gel electrophoresis (PAGE) in the presence of Triton X-100. The HPLAPs were undetectable or only slightly detectable by PAGE in the absence of Triton X-100. The HPLAPs were detected in all sera sampled during the last trimester of pregnancy. The catalytic activities of total placental alkaline phosphatase (TPLAP) and HPLAPs were correlated (r = 0.96) and the ratio of HPLAPs/TPLAP catalytic activity was 0.20 (0.06) (mean and SD) in 40 serum samples from pregnant women. The HPLAPs appear to be formed from a common dimeric placental alkaline phosphatase (PLAP) (common-PLAP), as judged by the fact that they were formed again after removal of HPLAPs from serum by gel filtration. The formation of HPLAPs was more prominently observed with the faster fractions of gel filtration. The apparent molecular mass of the HPLAPs in pregnancy serum was 720 KDa by gel filtration. HPLAPs were not converted to common-PLAP by phosphatidylinositol-specific phospholipase (PIPL) C and PIPL-D treatments. The HPLAPs were selectively incorporated into liposomes consisting of phosphatidylcholine/cholesterol, and most of the PIPL-D-treated PLAP could from HPLAPs, while a small amount of PLAP could not form HPLAPs. On the other hand, HPLAPs in pregnant women's sera and HPLAPs prepared from partially purified PLAP in vitro could be converted to common-PLAP by brief treatment with subtilisin. However, the highly purified PLAP could not form HPLAPs in the presence of Triton X-100. These results suggest that PIPL-D-resistant and PLAP-associated serum protein may regulate the conversion of PLAP to HPLAP in the presence of Triton X-100.
我们通过在Triton X - 100存在的情况下进行聚丙烯酰胺凝胶电泳（PAGE），检测了正常孕妇血清中高分子量胎盘碱性磷酸酶（HPLAPs）的出现情况。在没有Triton X - 100的情况下，通过PAGE无法检测到HPLAPs或只能略微检测到。在妊娠晚期采集的所有血清中都检测到了HPLAPs。总胎盘碱性磷酸酶（TPLAP）和HPLAPs的催化活性具有相关性（r = 0.96），在40份孕妇血清样本中，HPLAPs/TPLAP催化活性的比值为0.20（0.06）（平均值和标准差）。从凝胶过滤从血清中去除HPLAPs后它们会再次形成这一事实判断，HPLAPs似乎由一种常见的二聚体胎盘碱性磷酸酶（PLAP）（普通 - PLAP）形成。在凝胶过滤的较快组分中更明显地观察到了HPLAPs的形成。通过凝胶过滤，妊娠血清中HPLAPs的表观分子量为720 kDa。HPLAPs经磷脂酰肌醇特异性磷脂酶（PIPL）C和PIPL - D处理后不会转化为普通 - PLAP。HPLAPs被选择性地整合到由磷脂酰胆碱/胆固醇组成的脂质体中，并且大多数经PIPL - D处理的PLAP可以形成HPLAPs，而少量的PLAP不能形成HPLAPs。另一方面，孕妇血清中的HPLAPs和体外从部分纯化的PLAP制备的HPLAPs经枯草杆菌蛋白酶短暂处理后可转化为普通 - PLAP。然而，高度纯化的PLAP在Triton X - 100存在的情况下不能形成HPLAPs。这些结果表明，在Triton X - 100存在的情况下，PIPL - D抗性且与PLAP相关的血清蛋白可能调节PLAP向HPLAP的转化。
