Binding Properties of the Human Complement Protein Clq

The interaction between human Clq and immunoglobulins was measured quantitatively by determining the ability of IgG, IgM, and (Fc) 5µ to inhibit the binding of 125 I-labeled Clq to IgM covalently linked to cyanogen bromide activated Sepharose. The following inhibition constants were determined: K i...

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Bibliographic Details
Published in:The Journal of biological chemistry 1973-04, Vol.248 (8), p.2818-2823
Main Authors: Sledge, C R, Bing, D H
Format: Article
Language:English
Subjects:
Amines
Calcium
Centrifugation, Density Gradient
Chromatography, DEAE-Cellulose
Complement System Proteins
Humans
Immunoglobulin Fc Fragments
Immunoglobulin G
Immunoglobulin M
Iodine Isotopes
Kinetics
Polysaccharides
Protein Binding
Thyroid Function Tests
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Summary:The interaction between human Clq and immunoglobulins was measured quantitatively by determining the ability of IgG, IgM, and (Fc) 5µ to inhibit the binding of 125 I-labeled Clq to IgM covalently linked to cyanogen bromide activated Sepharose. The following inhibition constants were determined: K i for IgM = 6.42 x 10 -6 m ; K i for (Fc) 5µ = 4.35 x 10 -6 m ; and K i for IgG = 1.10 x 10 -4 m . The heat aggregation of IgM and IgG increased the ability of these proteins to bind 125 I-labeled Clq, but had no significant effect on the binding properties of (Fc) 5µ . The binding between the 125 I-labeled Clq and the IgM-Sepharose complex was inhibitable with aromatic and alkyl diamino compounds. The most potent inhibitor was 2,5-diaminotoluene.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(19)44080-5