Proteomic analysis of the biomineralization of spherical Brushite produced from a wheat bran aqueous extract

Wheat bran aqueous extracts provide phosphate ions and other necessary but unknown biomolecules for synthesizing spherical microparticles of dicalcium phosphate dihydrate or Brushite, which is interesting for the food industry due to its delivering nutraceuticals properties. This study tests the hypothesis that proteins are the scaffold biomolecules over which the Brushite crystals grow. Brushite was synthesized from the wheat bran aqueous extract by adding calcium ions. Precipitated particles were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive, and infrared spectroscopies, corroborating a single Brushite phase. The Brushite particles were demineralized for searching and identifying intracrystalline proteins through mass spectroscopy and bioinformatics. Six hundred and seventy-six proteins were identified in the Brushite and analyzed by their relative abundance and intrinsic disorder, giving 20 top proteins as scaffold candidates. Additionally, wheat bran aqueous extract was subjected to size exclusion chromatography to explore if a fraction is responsible for the Brushite synthesis. Four chromatographic fractions were obtained and treated as the aqueous extract to induce mineralization. Three fractions produced Brushite, from which two produced spherical brushite particles with diameters between 50 and 200 mu m. Particle size and morphology in one of the latter fractions matched those precipitated by the raw aqueous extract. Results strongly suggest that specific proteins in the wheat bran aqueous extract may have a role as a scaffold in spherical Brushite biomineralization.

Automated summary

Wheat bran aqueous extracts contribute to the synthesis of spherical microparticles of dicalcium phosphate dihydrate or Brushite, which has potential applications in the food industry. Proteins in the extract were identified as scaffold biomolecules for the growth of Brushite crystals. Size exclusion chromatography revealed specific fractions responsible for Brushite synthesis. Results suggest that certain proteins in the wheat bran aqueous extract play a role as a scaffold in spherical Brushite biomineralization.