The hydroxyapatite-binding regions of a rat salivary glycoprotein.
The regions of a salivary sulphated glycoprotein which are involved in its attachment to hydroxyapatite (Biogel HTP) have been characterised. The sulphated glycoprotein, a 35S-labelled preparation from mixed palatal and buccal minor gland secretions of the rat was bound onto hydroxyapatite and the resultant glycoprotein-hydroxyapatite complex was sequentially digested with pronase E and alpha-L-fucosidase, a treatment which released 86.8% +/- 1.7% of the radioactivity of the initially bound glycoprotein. The fragments which remained attached to the hydroxyapatite after enzymic digestion were fractionated on Sephadex G-25 and analysed for carbohydrate and amino acid components. A range of amino acids were detected which could reflect both glycosylated and non-glycosylated-binding regions. Sialic acid, although considered to be involved in the attachment process was not detected in any of the fragments remaining after enzymic digestion, a finding which provides indirect evidence that the enzymically liberated products do not subsequently re-attach to the hydroxyapatite surface. The notable feature of the fractions with average Mr estimated at 1000 or less is the high proportion of N-acetylhexosamine and N-acetylgalactosamine. It is apparent that the hexosamine residues, which normally bear the ester sulphate moieties of sulphated glycoproteins, play an important role in the attachment of sulphated glycoproteins to hydroxyapatite.
Embery
G
G
Department of Basic Dental Science, Dental School, University of Wales College of Medicine, Heath Park, Cardiff, U.K.
Green
D R
DR
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D051152:Clusterin; D017886:Durapatite; D006023:Glycoproteins / Q000032:analysis* / Q000378:metabolism; D006595:Hexosamines / Q000032:analysis; D006882:Hydroxyapatites / Q000378:metabolism*; D018832:Molecular Chaperones; D009005:Monosaccharides / Q000032:analysis; D051381:Rats; D012469:Salivary Glands / Q000378:metabolism*; D012470:Salivary Glands, Minor / Q000378:metabolism*; D012471:Salivary Proteins and Peptides / Q000032:analysis* / Q000378:metabolism
D000596:Amino Acids; D051152:Clusterin; D006023:Glycoproteins; D006595:Hexosamines; D006882:Hydroxyapatites; D018832:Molecular Chaperones; D009005:Monosaccharides; D012471:Salivary Proteins and Peptides; D017886:Durapatite