Monoclonal antibodies that recognize minimal differences in the three-dimensional structures of metal-chelate complexes.
Immunization of BALB/c mice with a cadmium-chelate-protein conjugate resulted in the isolation of two hybridoma cell lines (A4 and E5) that synthesized antibodies with different variable regions, but similar metal-chelate affinity. The ability of these two monoclonal antibodies to interact with 12 different metal-chelate complexes was studied using the KinExA 3000 immunoassay instrument. The two antibodies showed the highest affinity for cadmium and mercury complexes of ethylenediamine N,N,N',N'-tetraacetic acid (EDTA). The E5 antibody bound to EDTA complexes of cadmium and mercury with equilibrium dissociation constants (K(d)) of 1.62 x 10(-)(9) M and 3.64 x 10(-)(9) M, respectively. The corresponding values for the A4 antibody were 14.7 x 10(-)(9) M and 3.56 x 10(-)(9) M. Addition of a cyclohexyl ring to the EDTA backbone increased the affinity of E5 for the metal-chelate haptens, while decreasing the binding of A4 to the same haptens. Based on available crystal structures, molecular models were constructed for five different divalent metal-chelate complexes. The models were compared to determine structural features of the haptens that may influence antibody recognition. Difference distance matrixes were used to identify areas of the metal-chelate haptens that differed in three-dimensional space. Antibody affinity correlated well with the extent of total structural difference for these metal-EDTA complexes.
Jones
R Mark
RM
Department of Ophthalmology, Tulane University Health Sciences Center, New Orleans, Louisiana 70112, USA.
Yu
Haini
H
Delehanty
James B
JB
Blake
Diane A
DA
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000915:Antibody Affinity; D002104:Cadmium / Q000276:immunology*; D002417:Cattle; D004492:Edetic Acid / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D007114:Immunization; D007143:Immunoglobulin Heavy Chains / Q000737:chemistry; D007147:Immunoglobulin Light Chains / Q000737:chemistry; D007135:Immunoglobulin Variable Region / Q000737:chemistry; D008628:Mercury / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013329:Structure-Activity Relationship; D013816:Thermodynamics
D000911:Antibodies, Monoclonal; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D002104:Cadmium; D012710:Serum Albumin, Bovine; D004492:Edetic Acid; D008628:Mercury