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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The two anti-ferritin monoclonal antibodies of mouse IgG2a subclass, G10 and F11, are described that have similar affinity to human spleen ferritin and identical protein A-binding affinity. Antigen binding was shown to change significantly the protein A-binding parameters of the IgG2a antibodies. Antigen-induced conformational changes result in enhanced protein A-binding affinity of the G10 antibody while reduced affinity of the F11 antibody. Antigen binding does not change inherently low affinity of the anti-ferritin IgG1 antibody C5 to protein A. Differential scanning calorimetry revealed that the enthalpy and Gibbs free energy of denaturation for G10 was respectively by 19 and 29% higher than the corresponding parameters for F11. The lower structural energetics of F11 is associated with the lack of a calorimetrically revealed folding unit that may be responsible for distinct interaction between the antigen-binding and protein A-binding sites. This work provides experimental demonstration of the fact that functionally significant interactions between the two spatially remote recognition sites in antibodies of the same heavy chain isotype can be modulated by relatively small structural variations that also result in different thermodynamic stability.
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PMID:Thermodynamic stability of immunoglobulins and allosteric interactions with ferritin and protein A: distinct properties of the two antibodies of IgG2a subclass. 955 32

Two IgG2a monoclonal antibodies (G10 and F11) are described which have similar affinity for human spleen ferritin and identical protein A-binding affinity. The two mAbs display changes in protein A-binding affinity following binding of the antigen to its specific recognition site in the variable domains. However, while antigen-induced conformational changes in G10 enhance its affinity to protein A, interaction of F11 with ferritin results in a significant decrease in protein A-binding affinity. In contrast to the IgG2a antibodies, using a mouse IgG1 antiferritin antibody (C5) high-affinity binding of the antigen does not change an inherently low ability to bind protein A. Differential scanning calorimetry revealed that the enthalpy and Gibb's free energy of thermal unfolding for G10 was 19% and 23% higher, respectively, than the corresponding parameters for F11. The lower structural energetics of F11 are associated with the absence of a calorimetrically revealed folding unit, which may be responsible for interactions between the antigen-binding site and the protein A-binding site. This study provides the first demonstration that functionally significant interactions between two recognition sites in antibodies of the same subclass can be modulated by subclass-independent structural variations associated with different thermodynamic stability.
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PMID:Two high-affinity monoclonal IgG2a antibodies with differing thermodynamic stability demonstrate distinct antigen-induced changes in protein A-binding affinity. 977 83

Effects of four organic solvents--methanol, trifluoroethanol, dimethylsulfoxide, and dimethylformamide (DMF)--on the ferritin-binding activity of three monoclonal mouse antibodies of IgG2a and IgG1 subclasses were studied. The ferritin-binding constants of monoclonal antibodies G10 and F11 (the IgG2a subclass) were increased 2-6-fold after incubation with DMF and removal of the organic solvent by gel filtration. The maximum effect on the F11 antibodies was found in the presence of 5-13% DMF and on the G10 antibodies at 11-40% DMF. The effect remained after the removal of DMF from the incubation medium, and this suggests that the incubation with DMF resulted in irreversible conformational changes of the antibodies and in production of active conformers of the G10 and F11 antibodies. These conformations occurred within 15-60 min. The long-term stability and the fluorescence of the antibodies exposed to DMF suggest that the conformational changes were not global, but involved small and relatively independent structural elements of the antibodies, either of hypervariable CDR loops in variable domains or of the hinge region of the antibodies. The affinity of the C5 antibodies of the mouse IgG1 subclass was decreased after incubation with DMF. The activation was a solvent-specific effect because incubation of the G10 antibodies with methanol and dimethylsulfoxide decreased the affinity for the antigen, and incubation with trifluoroethanol virtually did not affect it. Relatively small changes in the antigen-binding activity of the antibodies were found even after the incubation with 5% organic solvent.
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PMID:Antigen-binding activity of monoclonal antibodies after incubation with organic solvents. 1111 41

Conformational changes were induced in human spleen ferritin by partial or complete removal of iron, and the immunoreactivity of the ferritin samples with variable iron content was analyzed. We established that a decrease in iron content resulted in bimodal changes in immunoreactivity of the epitopes recognized by the monoclonal antibodies G10 and F11. Immunoreactivity demonstrated a 3-6-fold decrease on lowering iron content from 800 to 40 atoms per protein molecule, followed by a sharp (4-14-fold) increase that was observed when low-iron ferritin was converted to iron-free apoferritin. These bimodal changes suggest the presence of more than two conformational states of ferritin with local alterations of the epitopes recognized by the monoclonal antibodies. The global conformation of ferritin, however, remained essentially unaltered, as demonstrated by ferritin interaction with polyclonal antibodies. Together, the results indicate that local conformational changes in the ferritin protein shell occur on progressive iron removal that results in low-iron and iron-free forms of ferritin. These changes are most clearly seen in apoferritin when compared to low-iron ferritin.
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PMID:Local conformational changes in ferritins with variable iron content. 1238 12