Claussen M, Zapf J, Braulke T
Institute for Biochemistry II, University of Göttingen, Germany.
Endocrinology. 1994 Apr;134(4):1964-6. doi: 10.1210/endo.134.4.7511097.
Incubation of iodinated recombinant human insulin-like growth factor binding protein (rhIGFBP)-5 with pregnancy serum or amniotic fluid resulted in the formation of 22- and 15 kDa fragments. Non-pregnancy serum did not contain IGFBP-5 proteolytic activity. Size fractionation revealed the proteolytic activity both in serum and amniotic fluid in a > 100 kDa fraction which co-eluted in gel filtration with proteins of approx. 200 kDa. The IGFBP-5 protease activity was inhibited by EDTA, phenanthroline and PMSF. The formation of proteolytic fragments was also observed using 125I labeled rhIGFBP-3 and -4 but not with rhIGFBP-1 or -6 as substrate. The data demonstrate that pregnancy serum and amniotic fluid contain a very similar cation-dependent serine protease which degrades IGFBP-3, -4 and -5.
将碘化重组人胰岛素样生长因子结合蛋白（rhIGFBP）-5与妊娠血清或羊水一起孵育，会形成22 kDa和15 kDa的片段。非妊娠血清不含有IGFBP-5蛋白水解活性。尺寸分级显示血清和羊水中的蛋白水解活性存在于大于100 kDa的级分中，该级分在凝胶过滤中与约200 kDa的蛋白质共洗脱。IGFBP-5蛋白酶活性受到EDTA、菲咯啉和PMSF的抑制。以125I标记的rhIGFBP-3和-4为底物时也观察到蛋白水解片段的形成，但以rhIGFBP-1或-6为底物时未观察到。数据表明，妊娠血清和羊水含有一种非常相似的阳离子依赖性丝氨酸蛋白酶，可降解IGFBP-3、-4和-5。
