Large intramolecular movement in human complement protein C3 induced by methylamine. A small-angle scattering study using monoclonal antibodies as markers.

摘要: The reaction of methylamine with complement protein C3, which involves cleavage a labile thiol ester bond, yields large intramolecular rearrangement. This is shown by small-angle neutron and X-ray scattering using Fab antibody as marker. For the C3(Fab) 1:1 complex, an increase in radius gyration, R, from 4.6 nm to 6.0 nm. In absence corresponding R values 4.4 5.1 It estimated that methylamine-induced may correspond movement epitope position 5 away centre gravity C3 molecule. agreement this finding, maximum distance within complex increases 16 22 result reaction. order explain conformational change, it tentatively suggested bond leads domain rotation idea, data consistent model enables globular molecule rotate without redistributing molecular mass more than radii gyration observed.