Organic biopolymers of venus clams: collagen-related matrix in the bivalve shells with crossed-lamellar ultrastructure

Oluwatoosin B. A. Agbaje*, J. Gabriel Dominguez, Dorrit E. Jacob

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    10 Citations (Scopus)
    55 Downloads (Pure)

    Abstract

    Background: Biochemical studies and spectroscopic techniques have shown that chitin-silk fibroins are common in nacroprismatic bivalve shells. However, the nature of organic biopolymers in the less well studied shell architectures, such as crossed lamellar shells, remain unknown. Here, two venus shells, Callista disrupta and Callista kingii, with crossed lamellar ultrastructure have been studied.

    Methods: We employed thermal gravimetric analysis, optical-, confocal- and scanning electron-microscopes, gel-sodium dodecyl sulfate (gel-SDS), FTIR, ultra-performance liquid chromatography and high-performance anion-exchange chromatography system with pulsed amperometric detection to analyse organic macromolecules in the shells.

    Results: Thermal analysis showed a low concentration of organic macromolecules in C. disrupta (1.38 wt%) and in C. kingii (1.71 wt%). A combination of biochemical protocols, including Calcofluor White staining and FTIR spectroscopic assessment, indicate that amino-polysaccharide chitin together with proteins, are present in the organic scaffolding of the shells. Scanning electron microscope of insoluble acid biopolymer extracts as well as FTIR technique show that the hierarchical structural organizations of organic biopolymers consist collagen-related matrix. Our histochemical fixing and staining techniques reveal many discrete proteins and glycoproteins from soluble organic macromolecules on the gel-SDS. We show here ‘singlet’ and ‘doublet’ glycosaminoglycan bands that are far above 260 kDa.

    General significance/conclusions: The presence of collagen matrix in Callista shells shows promise for the new source of biomaterials. Most importantly, the structural organization of the proteinaceous motif is predominantly helical structures and not silk-fibroin unlike in nacreous bivalve shells.

    Original languageEnglish
    Article number100939
    Pages (from-to)1-8
    Number of pages8
    JournalBiochemistry and Biophysics Reports
    Volume26
    DOIs
    Publication statusPublished - Jul 2021

    Bibliographical note

    Copyright the Author(s) 2021. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

    Keywords

    • Polysaccharides
    • Chitin
    • Collagen
    • Glycosaminoglycans
    • Biomineralization
    • ATR-FTIR

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