Structural probe analysis on the attachment of salivary glycoproteins to hydroxyapatite using Fourier-transformed infrared spectroscopy.

The mechanisms of interaction between a salivary glycoprotein and hydroxyapatite has been studied using Fourier-transformed infrared spectroscopy. The spectra of the reacted mixtures showed evidence of change at 1,230-1,250 cm-1 due to the S = O stretching vibrations of the ester sulphate groups and at 775 and 828 cm-1 attributed to sulphate groups in the 6-position of N-acetylgalactosamine. Evidence of amide change in the regions of 1,670 and 1,550 cm-1 is also apparent due to involvement of the polypeptide region. It is proposed that the exposed parts of the protein core are involved in the attachment of the glycoprotein to hydroxyapatite with the main interactive residues being the sulphate groups present on the carbohydrate apo-protein moiety. The results are considered of value in relation to mechanisms involved in the coating of exposed apatite surfaces during the formation of acquired enamel pellicle.