Nanostructure ordering of proteoglycans of some biological objects

Abstract

This paper reports on the results of systematic X-ray diffraction investigations into the structure of proteoglycans of the mucus and the extracellular matrix of biological tissues. The small-angle X-ray diffraction patterns of different native and modified tissues of man and animals are measured using synchrotron radiation. A comparative study of the structure of mucins from the mammal and invertebrate mucus is performed. It is demonstrated that the X-ray diffraction patterns of the mammal and invertebrate mucus are very similar to each other and exhibit a number of sharp diffraction rings with a spacing of 4.5 nm and its higher orders due to the highly ordered structure of giant proteoglycan molecules. It is revealed that the proteoglycan structure undergoes a transformation upon interaction with calcium cations. The type of X-ray diffraction pattern ("with a 4.5-nm ring" and "without a ring") for intact tissues can be reversibly changed by treating the tissues in solutions of salts or chelating agents. The inference is made that the X-ray diffraction patterns of tissues can be used as markers for the structural transformation of the extracellular matrix under different exogenous actions.