International
Tables for Crystallography Volume F Crystallography of biological macromolecules Edited by M. G. Rossmann and E. Arnold © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. F. ch. 19.4, p. 443
Section 19.4.6. Examples
aDepartment of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA, and bDepartments of Chemistry and Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA |
An early result that changed ideas about nucleosome organization came from measurements relying on the difference in protein and DNA densities (Baldwin et al., 1975; Bradbury et al., 1976
). Information on the organization of serum lipoproteins was also based on intrinsic scattering differences (Stuhrmann et al., 1975
; Atkinson & Shipley, 1984
). The contrast between RNA and protein was used in early ribosome measurements (Crichton et al., 1977
; Moore et al., 1974
). Recent examples include detergent binding to membrane proteins (Timmins et al., 1991
) and the study of membrane protein–lipid complexes (Jeanteur et al., 1994
). Elegant use of contrast variation resulted in a structural explanation of the anti-cooperative binding of tRNA to synthetase, which had resisted study by other methods (Dessen et al., 1978
).
In some applications, use has been made of contrast matching a large part of a complex to study a component with a contrasting scattering density. Examples include studies of ribosomal proteins in situ (Nierhaus et al., 1983; Nowotny et al., 1994
), proteins of the DNA-dependant RNA polymerase (Stöckel et al., 1980a
), studies of muscle proteins (Stone et al., 1998
) and a view of a membrane protein in a lipid bilayer (Hunt et al., 1997
).
Some applications of the spin contrast variation method have appeared (Junemann et al., 1998; Nierhaus et al., 1998
).
Many recent measurements use specific labelling and combine information with data from small-angle X-ray scattering. Studies of ligand binding (Bilgin et al., 1998), hydration layers (Svergun et al., 1998
), troponin complexes (Olah et al., 1994
) and ribosomes (Svergun et al., 1996
) are examples that illustrate the approaches.
By measuring distances and radii of gyration, models of some large complexes have been created. These include a model of the relative positions of all 21 proteins in the small ribosomal subunit from E. coli (Capel et al., 1987), a model of seven proteins from the large subunit (May et al., 1992
) and a model of the DNA-dependant RNA polymerase (Stöckel et al., 1980b
). Intramolecular conformational states of cholesterol esters have been observed using distance measurements on molecules chemically labelled in different regions (Burks & Engelman, 1981
).
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