Figure 1. Strategies for determining statherin structure on HAP and summary results for the N-terminal domain. The sequence of statherin is given, along with the ¹³C-labeled amino acid positions. DRAWS and DQDRAWS determine the backbone torsional angle phi at the pSpS position, while REDOR was used to determine the (i) to (i+4) ¹³C-¹⁵N hydrogen bonding distances between S₃ and F₇, and L₈ and G₁₂. Peptides were synthesized by standard F_moc solid-phase peptide synthesis strategies, and phosphorylation was performed after protein synthesis for serine ¹³C=O enriched samples. The HAP crystals had a surface area of 80 m²/g, and adsorption of statherin was carried out at 40 µM for two hours, followed by extensive washing in PBS to remove loosely adsorbed protein.