Direct observation of phenylalanine orientations in statherin bound to hydroxyapatite surfaces

J Am Chem Soc. 2012 May 30;134(21):8750-3. doi: 10.1021/ja301711w. Epub 2012 May 18.


Extracellular biomineralization proteins such as salivary statherin control the growth of hydroxyapatite (HAP), the principal component of teeth and bones. Despite the important role that statherin plays in the regulation of hard tissue formation in humans, the surface recognition mechanisms involved are poorly understood. The protein-surface interaction likely involves very specific contacts between the surface atoms and the key protein side chains. This study demonstrates for the first time the power of combining near-edge X-ray absorption fine structure (NEXAFS) spectroscopy with element labeling to quantify the orientation of individual side chains. In this work, the 15 amino acid N-terminal binding domain of statherin has been adsorbed onto HAP surfaces, and the orientations of phenylalanine rings F7 and F14 have been determined using NEXAFS analysis and fluorine labels at individual phenylalanine sites. The NEXAFS-derived phenylalanine tilt angles have been verified with sum frequency generation spectroscopy.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Durapatite / metabolism*
  • Models, Molecular
  • Molecular Sequence Data
  • Phenylalanine*
  • Protein Binding
  • Protein Structure, Tertiary
  • Salivary Proteins and Peptides / chemistry*
  • Salivary Proteins and Peptides / metabolism*
  • Surface Properties
  • X-Ray Absorption Spectroscopy*


  • STATH protein, human
  • Salivary Proteins and Peptides
  • Phenylalanine
  • Durapatite