Establishment of a novel refinement workflow for oligopeptides containing branched-chain amino acids with cyclodextrins

Peptides containing branched-chain amino acids (BCAAs) are recognized for their diverse physiological functions; however, effective methods for their target refinement remain underdeveloped. This study introduced a novel approach utilizing the cavity structure of cyclodextrins, along with specific adsorption (50 % ethanol, 50 °C) and crystallization conditions (75 % ethanol, 4 °C), to selectively isolate BCAA-containing oligopeptides from Antarctic krill. Following refinement, the relative BCAA content was elevated to 1.70-fold compared to the original peptide mixture, with the number and abundance of BCAA-containing peptides reaching 95.00 % and 94.96 %, respectively. Principal component and spectral analysis demonstrated that initial ethanol concentration and cyclodextrin cavity size significantly influenced the peptidome profiles by modulating peptide-cyclodextrin interactions. This study provides a comprehensive exploration of the molecular interactions between peptides and cyclodextrins, highlighting a novel application of cyclodextrins for target peptide isolation and offering deeper insights into the principles governing cyclodextrin inclusion.