Poster Presentation 2014 International Biophysics Congress

Synchrotron radiation CD conformational studies on hydroxyapatite statherin binding in solution (#490)

Robert Janes 1 , Paul Anderson 2
  1. School of Biological Sciences, Queen Mary University of London, London, UK
  2. School of Dentistry, Queen Mary University of London, London, UK

            Statherin is a small salivary protein 43 residues in length (STN43).  One key function of this protein is to protect tooth enamel surfaces from caries and erosive attack through inhibition of the growth of dissolution pit nuclei. Key to this function is statherin's changing its conformational structure on binding to the inorganic component of enamel mineral, namely calcium hydroxyapatite (HAP), through N-terminally located residues.  Our objectives were to monitor this conformational change for the first time in an aqueous solution and for this we utilised a synthesised peptide which comprised the N-terminal 21 residues of statherin (STN21).  To following the nature and strength of statherin binding to the HAP surface we used Synchrotron Radiation Circular Dichroism (SRCD) because of the higher photon flux and detector geometry of these machines which are optimal for handling highly scattering samples.

The results suggest that STN21 increases its alpha-helical content on binding to HAP and that this binding is stable up to around 50OC indicating a high degree of binding affinity.  The resultant spectral characteristics suggests not only an increase in helicity but that statherin may be orientated relative to the planar crystalline surface of HAP, features important to its cariostatic protective properties.

(Supported in part by the U.K. Biotechnology and Biological Sciences Research Council)