In vitro binding and in vivo clearance of human alpha 2-macroglobulin after reaction with endoproteases from four different classes.
Feldman SR, Ney KA, Gonias SL, Pizzo SV. In vitro binding and in vivo clearance of human alpha 2-macroglobulin after reaction with endoproteases from four different classes. Biochem Biophys Res Commun. 1983 Jul 29;114(2):757-62.
The binding of human alpha 2-macroglobulin complexed with trypsin,
papain, thermolysin and cathepsin-D to murine macrophages was studied
at 4 degrees C.Similar dissociation constants (0.4 nM) were
determined for all of the complexes except alpha
2-macroglobulin-cathepsin-D (0.7 nM). Radioiodinated
alpha2-macroglobulin-protease complexes were injected into mice, and
the clearance studied. Native alpha 2-macroglobulin cleared slowly,
as previously reported,while greater than 50% of the complexes
formed with trypsin, papain andthermolysin cleared in less than 5
min. The clearance of alpha2-macroglobulin-cathepsin-D was biphasic,
suggesting that only about half thealpha 2-macroglobulin was present
in a reacted complex.