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Title
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Crystallographic structure studies of an IgG molecule and an Fc fragment.
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Authors
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R.Huber,
J.Deisenhofer,
P.M.Colman,
M.Matsushima,
W.Palm.
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Ref.
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Nature, 1976,
264,
415-420.
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PubMed id
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Abstract
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The crystal structures of a human IgG antibody molecule Kol and a human Fc
fragment have been determined at 4-A and 3.4-A resolution respectively, by
isomorphous replacement. The electron-density maps were interpreted in terms of
immunoglobulin domains based on the Rei and McPC 603 models (Kol) and by
model-building (Fc). The Fab parts of Kol have a different quaternary structure
from that observed in isolated crystalline Fab fragments, there being no
longitudinal V-C contact in Kol. The Fc part C terminal to the hinge is
disordered in the Kol crystals. It is suggested that the Kol molecule is
flexible in solution, whereas fragments are rigid. In the Fc fragment both CH3
and CH2 show the immunoglobulin fold. The CH3 dimer aggregates as CH1-CL while
CH2 are widely separated from each other. The carbohydrate bound to Fc is in
fixed position. From these structures a hypothetical liganded antibody molecule
has been constructed, which is assumed to be rigid.
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