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Detection of small conformational changes of proteins by small‐angle scattering
Author(s) -
Durchschlag H.,
Zipper P.,
Wilfing R.,
Purr G.
Publication year - 1991
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889891004831
Subject(s) - radius of gyration , chemistry , small angle x ray scattering , small angle scattering , circular dichroism , conformational change , crystallography , scattering , citrate synthase , neutron scattering , enzyme , biochemistry , polymer , physics , organic chemistry , optics
In the past the technique of small‐angle scattering has been a powerful tool for studying conformational changes of proteins which occur, for example, upon binding with ligands. Results obtained by different authors from X‐ray and neutron experiments on a variety of proteins and under various conditions have been compiled. This offers the possibility of comparing the extent of changes in the molecular parameters investigated ( e.g. change of the radius of gyration). Problems encountered with the detection of small changes are discussed. As an example, conformational changes of the enzyme citrate synthase upon substrate binding (oxaloacetate) are presented. X‐ray crystallography had already found distinct changes between open and closed forms of the enzyme. Small‐angle X‐ray scattering studies registered slight changes of some parameters in solution. These changes could be paralleled with the results of other solution techniques (UV absorption, fluorescence and circular dichroism spectroscopy, analytical ultracentrifugation). The results found for citrate synthase are also compared with previous findings for malate synthase, an enzyme of similar enzymatic function. Above all, this study shows that care has to be taken when studying small conformational changes. It is absolutely necessary to use different methods and conditions and to study the problem from different points of view to avoid pitfalls.