Structural investigation of porcine stomach mucin by X-ray fiber diffraction and homology modeling

The basic understanding of the three dimensional structure of mucin is essential to understand its physiological function. Technology has been developed to achieve orientated porcine stomach mucin molecules. X-ray fiber diffraction of partially orientated porcine stomach mucin molecules show d-spacing signals at 2.99, 4.06, 4.22, 4.7, 5.37 and 6.5 Å. The high intense d-spacing signal at 4.22 Å is attributed to the antiparallel β-sheet structure identified in the fraction of the homology modeled mucin molecule (amino acid residues 800–980) using Nidogen–Laminin complex structure as a template. The X-ray fiber diffraction signal at 6.5 Å reveals partial organization of oligosaccharides in porcine stomach mucin. This partial structure of mucin will be helpful in establishing a three dimensional structure for the whole mucin molecule.