1zvo
From Proteopedia
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Semi-extended solution structure of human myeloma immunoglobulin D determined by constrained X-ray scattering
Overview
Human immunoglobulin D (IgD) occurs most abundantly as a membrane-bound, antibody on the surface of mature B cells (mIgD). IgD possesses the, longest hinge sequence of all the human antibody isotypes, with 64, residues connecting the Fab and Fc fragments. A novel rapid purification, scheme of secreted IgD from the serum of an IgD myeloma patient using, thiophilic (T-gel) and lectin affinity chromatography gave a stable, homogeneous IgD preparation. Synchrotron X-ray scattering and analytical, ultracentrifugation of IgD identified the solution arrangement of its Fab, and Fc fragments, and thereby its hinge structure. The Guinier X-ray, radius of gyration R(G) of 6.9(+/-0.1)nm showed that IgD is more extended, in solution than the immunoglobulin subclass IgA1 (R(G) of 6.1-6.2nm). Its, distance distribution function P(r) showed a single peak at 4.7nm and a, maximum dimension of 23nm. Velocity experiments gave a sedimentation, coefficient of 6.3S, which is similar to that for IgA1 at 6.2S. The, complete IgD structure was modelled using molecular dynamics to generate, IgD hinge structures, to which homology models for the Fab and Fc, fragments were connected. Good scattering curve fits were obtained with 18, semi-extended best fit IgD models that were filtered from 8500 trial, models. These best-fit models showed that the IgD hinge does not, correspond to an extended polypeptide structure. The averaged solution, structure arrangement of the Fab and Fc fragments in IgD is principally, T-shaped and flexible, with contribution from Y-shaped and inverted, Y-shaped structures. Although the linear sequence of the IgD hinge is much, longer, comparison with previous scattering modelling of IgA1 and IgA2(m)1, suggests that the hinge of IgA1 and IgD are more similar than might have, been expected, Both possess flexible T-shaped solution structures, probably reflecting the presence of restraining O-linked sugars.
About this Structure
1ZVO is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Semi-extended solution structure of human myeloma immunoglobulin D determined by constrained X-ray scattering., Sun Z, Almogren A, Furtado PB, Chowdhury B, Kerr MA, Perkins SJ, J Mol Biol. 2005 Oct 14;353(1):155-73. PMID:16157351
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