An immune complex selective affinity matrix utilizing a synthetic peptide.
A synthetic peptide possessing an amino acid sequence patterned on the globular head region of human complement component 1 subcomponent q (C1q) was tested for immunoglobulin binding. The peptide designated complementary binding peptide 2 (CBP2) was able to inhibit Staphylococcus aureus Protein A and human C1q from binding rabbit immunoglobulin at peptide concentrations for 50% inhibition of 1 and 10 microM, respectively. When attached to a solid-phase matrix in a column, CBP2 was able to bind immune complexes consisting of horseradish peroxidase plus rabbit antiperoxidase antibody or alkali-aggregated human immunoglobulins. A 1:4 mixture of immune complex to free immunoglobulin when passed over the CBP2 column demonstrated selective immune complex binding. Further controls established that CBP2 was in fact binding the immunoglobulin component of the immune complexes in a reversible fashion. The immune complex specificity of the column suggested a functional affinity was forming when CBP2 interacted with immune complexes. The possibility that the sequence of CBP2 is part of the immunoglobulin binding site of human C1q is discussed.
Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, Chicago, Illinois 60611.
M A
MA
Baumann
B E
BE
Anderson
D000595:Amino Acid Sequence; D000936:Antigen-Antibody Complex / Q000302:isolation & purification*; D001667:Binding, Competitive; D002846:Chromatography, Affinity / Q000379:methods*; D002942:Circular Dichroism; D015922:Complement C1q / Q000378:metabolism; D015195:Drug Design; D007074:Immunoglobulin G / Q000378:metabolism; D007136:Immunoglobulins / Q000378:metabolism; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D013205:Staphylococcal Protein A / Q000378:metabolism; D013329:Structure-Activity Relationship
D000936:Antigen-Antibody Complex; D007074:Immunoglobulin G; D007136:Immunoglobulins; D010455:Peptides; D013205:Staphylococcal Protein A; C044411:polymeric IgG; D015922:Complement C1q