Fig. 6.

αM–protease complex formation in vitro and in situ. (A) Image of a native gel showing the migration of purified native PZP and PZP–protease complexes. Putative PZP–protease complexes were generated by preincubation with chymotrypsin (chym) at a 2:1 molar ratio of PZP to chym for 30 min at 37 °C. (B) Native Western blot analysis showing putative αM–protease complexes in human pregnancy plasma. Heparinized human pregnancy plasma was incubated at 37 °C for 45 min in the presence or absence of 1 µM chym. An additional sample was held at 4 °C on ice for the same period (control). Blots probed for (i) PZP or (ii) α₂M are from the same experiment. The expected positions of the PZP–chym and α₂M–chym complexes are indicated. (C) The band corresponding to the native PZP dimer was quantified using densitometry in pregnancy plasma treated as described in B. The graph shows the mean PZP level relative to the control (n = 5 independent experiments ± SD).