Segmental flexibility of immunoglobulin G antibody molecules in solution: a new interpretation.

摘要: We propose a new model for the segmental flexibility of immunoglobulin G (IgG). The native and mildly reduced anti-5-(dimethylamino)naphthalene-1-sulfonyl (anti-dansyl) antibody was reexamined by nanosecond fluorescence spectroscopy using deconvolution lamp-shift corrections. rabbit antibodies used this study were purified dimers other aggregates. original results indicated that decay anisotropy involved two rotational correlation times. It suggested short time, phi s, represented flexible Fab arm motion over restricted angle long L, global tumbling molecule [Yguerabide, J., Epstein, H. F., & Stryer, L. (1970) J. Mol. Biol. 51, 573--590]. Our data indicate time primarily represents motions segments not entire molecule. This interpretation implies more IgG. Thus, in solution arms appear to move wide are 33 degrees as earlier model. Simple diffusion calculations evidence suggest s may represent V-module about switch peptides or twisting around its axis, whereas L wagging wobbling hinge region. faster occur small angles slower responsible most be much less restricted. biological function IgG changes resulting from disulfide cleavage interpreted terms proposed also demonstrate useful method comparison time-dependent steady-state polarization data.