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Chemical modification of α 2 ‐macroglobulin to generate derivatives that bind transforming growth factor‐β with increased affinity
Author(s) -
Webb Donna J.,
Gonias Steven L.
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)00598-x
Subject(s) - methylamine , chemistry , transforming growth factor , reagent , macroglobulin , dissociation (chemistry) , stereochemistry , dissociation constant , receptor , biophysics , biochemistry , biology , microbiology and biotechnology
α 2 ‐Macroglobulin (α 2 M) binds a number of cytokines, including transforming growth factor‐β1 (TGF‐β1) and TGF‐β2. The affinity of these interactions depends on the α 2 M conformation. In this investigation, we treated human α 2 M with cis ‐dichlorodiammineplatinum (II) ( cis ‐Pt), a crosslinking reagent that partially ‘locks’ the α 2 M conformation, and then with methylamine to generate a preparation (α 2 M‐P/M) consisting of stable α 2 M conformational intermediates. α 2 M‐P/M bound TGF‐β1 and TGF‐β2 with higher affinity than any other form of α 2 M studied to date. The equilibrium dissociation constants were 14 and 2 nM for TGF‐β1 and TGF‐β2, respectively. α 2 M‐P/M, at 100 nM, neutralized the activity of TGF‐β1 by about 75% in an endothelial cell proliferation assay. The equivalent concentration of native α 2 M or methylamine‐modified α 2 M had no effect. These studies demonstrate that the potential of α 2 M as a cytokine carrier and neutralizer may not be fully realized in either the native or completely activated conformations.