Compositional and structural characteristics of pepsin-soluble type I collagen from the scales of red drum fish, Sciaenops ocellatus

The type I pepsin-soluble collagen (type I PSC) from the red drum fish (Sciaenops ocellatus) scales was successfully purified by hydrophilic ultrafiltration (UF). The collagen purification process was appraised in depth and described in detail, respectively. Based on SDS-PAGE analysis, using proteomics analysis and Isoform-sequencing (Iso-Seq), it was confirmed to be the type I PSC, containing collagen alpha 1 and alpha 2 chains as the single components, with the absence of the non- collagenous proteins, non-type I collagens and potentially allergenic proteins. The type I PSC was verified to be non-denatured collagen monomers with integrated triple-helical structure using gel filtration chromatography (GFC), ion-exchange chromatography (IEC), reversed-phase HPLC (RP-HPLC), fourier transform infrared spectroscopy (FTIR), matrix-assisted laser desorption ionization-time of flight/mass spectrometry (MALDI-TOF/MS) and amino acid composition analysis. Thus, the accurate primary structures of the type I PSC with 100% matched peptide coverage were obtained for the first time. Additionally, our current study is the first to illustrate the protein component changes in collagen induced by hydrophilic UF and the primary structure changes in collagen molecules induced by pepsin solubilization.

Automated summary

The study successfully purified type I pepsin-soluble collagen from red drum fish scales using hydrophilic ultrafiltration, confirming it as non-denatured collagen monomers with integrated triple-helical structure and achieving 100% matched peptide coverage for the first time. Additionally, the research illustrated protein component changes in collagen induced by hydrophilic UF and primary structure changes in collagen molecules induced by pepsin solubilization.