X-ray diffraction study of structural stability of giant proteoglycan molecules of mucus

X-ray diffraction study of various native and modified gastrointestinal mucins was carried out using synchrotron radiation. The mucus X-ray patterns of mammals and invertebrates are very similar and display a large number of sharp diffraction rings at the spacing of about 4.65 nm, which are due to the helical packing of polysaccharide chains covalently connected to the protein core. A comparative analysis of the X-ray patterns obtained earlier by us from various samples of mucus and biological tissues showed that the 4.65(±0.15) nm spacing is a nanoscale structural invariant of giant proteoglycan molecules of both the mucus and the extracellular matrix of tissues. A role of structural dynamics of proteoglycan scaffolding of biological systems in mechanism of modifying adaptation of organisms to significant changes of temperature is discussed.