Dimeric, trimeric and tetrameric complexes of immunoglobulin G fix complement.

Details

Serval ID
serval:BIB_E50F621ED7A2
Type
Article: article from journal or magazin.
Collection
Publications
Title
Dimeric, trimeric and tetrameric complexes of immunoglobulin G fix complement.
Journal
Biochemical Journal
Author(s)
Wright J.K., Tschopp J., Jaton J.C., Engel J.
ISSN
0264-6021 (Print)
ISSN-L
0264-6021
Publication state
Published
Issued date
1980
Volume
187
Number
3
Pages
775-780
Language
english
Abstract
The binding of pure dimers, trimers and tetramers of randomly cross-linked non-immune rabbit immunoglobulin G to the first component and subcomponent of the complement system, C1 and C1q respectively, was studied. These oligomers possessed open linear structures. All three oligomers fixed complement with decreasing affinity in the order: tetramer, trimer, dimer. Complement fixation by dimeric immunoglobulin exhibited the strongest concentration-dependence. No clear distinction between a non-co-operative and a co-operative binding mechanism could be achieved, although the steepness of the complement-fixation curves for dimers and trimers was better reflected by the co-operative mechanism. Intrinsic binding constants were about 10(6)M-1 for dimers, 10(7)M-1 for trimers and 3 X 10(9)M-1 for tetramers, assuming non-co-operative binding. The data are consistent with a maximum valency of complement component C1 for immunoglobulin G protomers in the range 6-18. The binding of dimers to purified complement subcomponent C1q was demonstrated by sedimentation-velocity ultracentrifugation. Mild reduction of the complexes by dithioerythritol caused the immunoglobulin to revert to the monomeric state (S20,w = 6.2-6.5S) with concomitant loss of complement-fixing ability.
Keywords
Animals, Complement Activating Enzymes/metabolism, Complement C1/metabolism, Complement C1q, Complement Pathway, Classical, Immunoglobulin G/metabolism, Kinetics, Macromolecular Substances, Mathematics, Protein Binding, Rabbits
Pubmed
Web of science
Create date
24/01/2008 15:18
Last modification date
20/08/2019 16:08
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