Structural features of fab fragments of rheumatoid factor IgM-RF in solution

The structural features of the Fab fragments of monoclonal (Waldenstrom's disease) immunoglobulin M (I-M) and rheumatoid immunoglobulin M (lgM-RF) were studied by a complex of methods, including small-angle X-ray scattering (SAXS), electron spin resonance (ESR), and mass spectrometry (MS). The Fab-RF fragment was demonstrated to be much more flexible in the region of interdomain contacts, the molecular weights and the shapes of the Fab and Fab-RF macromolecules in solution being only slightly different. According to the ESR data, the rotational correlation time for a spin label introduced into the peptide sequence for Fab is twice as large as that for Fab-RF (21 +/- 2 and 11 +/- 1 ns, respectively), whereas the molecular weights of these fragments differ by only 0.5% (mass-spectrometric data), which correlates with the results of molecular-shape modeling by small-angle X-ray scattering. The conclusion about the higher flexibility of the Fab-RF fragment contributes to an understanding of the specificity of interactions between the rheumatoid factor and the anti-ens of the own organism. © 2008, Springer.

Keywords

Small angle scattering, Immunoglobulins, Electron spin resonance, Mass spectroscopy, Peptides, Rheumatic diseases

Citation

Volkov, V. V., Lapuk, V. A., Shtykova, E. V., Stepina, N. D., Dembo, K. A., Sokolova, A. V., Amarantov, S. V., Timofeev, V. O., Ziganshin, R. K., & Valamova, E. Y. (2008). Structural features of fab fragments of rheumatoid factor IgM-RF in solution. Crystallography Reports, 53(3), 466-473. doi:10.1134/S1063774508030140