SMALL‐ANGLE X‐RAY SCATTERING STUDIES OF THERMALLY‐INDUCED GLOBULAR PROTEIN GELS

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Abstract
Small‐angle X‐ray scattering has been applied to gels formed by heating globular proteins, in aqueous solution, above their unfolding temperatures. A number of BSA gels, previously characterised by electron microscopy, have been studied, and, by setting up theoretical models for the scattering process, the X‐ray data have been shown to be consistent with the microscope conclusions regarding network structure. It is concluded that the networks form by a linearly‐directed aggregation of unfolded, disc‐like, protein molecules, three‐dimensional geometry being achieved by occasional branching, and/or cross‐linking. Longrange inhomogeneities in network structure, easily observed by electron microscopy, and correlated with variations in pH or ionic strength, have an effect on X‐ray scattering, and hence the X‐ray method is sensitive not only to different network strand thicknesses, but to different degrees of uniformity as well.