Conformational analysis of an SRCRD-derived peptide on hydroxyapatite surfaces using dispersive calcium phosphate particles.

Hydroxyapatite (HAp), the major inorganic component of vertebrate bone and teeth, strongly interacts with organic molecules such as proteins, while the structural basis of protein binding to HAp remains unclear. Using solution NMR combined with HAp dispersive particles (DPs), we analyzed a peptide derived from a scavenger receptor cysteine-rich domain (SRCRD), a protein module found in salivary proteins that bind to tooth enamel. NMR analyses revealed that SRCRDpep adopted an elongated conformation on the surface of HAp, where acidic residues and aromatic side chains aligned with the Ca2+ spacing along the {001} plane. These findings highlight residue-specific recognition at the peptide-mineral interface and provide insights into the molecular mechanism of HAp binding.