Cementum Attachment Protein-Derived Peptides Modulate Brushite and Calcium Oxalate Crystallization In Vitro

Pathological mineralization involves the uncontrolled crystallization of calcium phosphate (brushite) and calcium oxalate, leading to renal calculi and ectopic calcifications. Peptides enriched in acidic or phosphorylated residues are potential crystal growth modulators due to their ability to interact with calcium-rich surfaces. This study investigated the in vitro effects of cementum attachment protein-derived peptides, CAP-pi and its phosphorylated analog CAP-pip, on brushite and calcium oxalate crystallization. By isolating these highly anionic motifs, this work introduces a novel biomimetic approach to investigate and modulate the physicochemical mechanisms driving pathological mineral deposition. Assays performed under physiological conditions were analyzed by scanning electron microscopy, Raman spectroscopy, and confocal microscopy, alongside molecular dynamics simulations to examine peptide-calcium oxalate interactions. Both peptides altered crystal growth patterns and lattice organization in a concentration-dependent manner. Peptide treatments induced marked morphological perturbations, promoted irregular and rosette-like habits, and modified vibrational profiles. Furthermore, confocal microscopy revealed selective adsorption onto specific crystallographic regions, whereas molecular dynamics demonstrated enhanced peptide-calcium coordination and interfacial stability for CAP-pip. Collectively, these findings establish phosphorylation as a key determinant of peptide-mineral interactions, providing mechanistic insight into how phosphopeptides regulate crystallization through surface-mediated modulation.