The proteomics of the freshwater pearl powder: Insights from biomineralization to biomedical application

Abstract

The freshwater pearl is one kind of valuable organic jewelry and traditional Chinese medicine (TCM). However, the molecular basis of matrix protein in pearl biomineralization and biomedical applications are largely unknown to date. In this study, the matrix proteins of water-soluble matrix, acid-soluble matrix and acid-insoluble matrix from the freshwater seedless pearl powder were detected using liquid chromatography-tandem mass spectrometry (LC-MS/MS) respectively, and identified against the transcriptomic database of the pearl sac. The results showed that a total of 190 proteins were identified in pearl proteomics, which was divided into eight categories by their potential biomineralization functions. The composition of pearl matrix proteins and the high frequency conserved domains like carbonic anhydrase, von Willebrand factor type A, tyrosinase and chitin binding 2 in protein sequences, implying that the “chitin-silk fibroin gel proteins–acidic macromolecules” model was suitable for description the pearl biomineralization process. Meanwhile, ninety-one of pearl matrix proteins could be classified into seven categories by their potential medical functions including wound healing, osteogenic property, antioxidant activity, neuro-regulation effects, skin lightening effect, anti-inflammatory and anti-apoptotic effects and other immunomodulatory property. In general, these results provided valuable new insights into not only the diversity of pearl matrix protein for mollusc biomineralization, but the molecular basis of pearl matrix proteins responsible for their diverse biological properties in TCM application. SignificanceThe significance of this study included the following points:1.A total of 190 proteins were identified in the freshwater pearl powder, providing valuable new insights into the complexity and diversity of pearl matrix protein in biomineralization.2.Pearl matrix proteins was divided into seven categories by their potential medical functions. This study, for the first time, attempted to unravel the molecular basis responsible for diverse biological properties of pearl powder in TCM application. We believe that this work will provide key basement and open a window for investigating the biological properties of matrix proteins and further illuminating the functional mechanism of pearl powder as TCM.