Applicability of the critical-chromatography concept to analysis of proteins: Dependence of retention times on the sequence of amino acid residues in a chain

The BioLCCC model of the chromatographic separation of biomacromolecules, which involves the concepts of the critical chromatography of polymers, is used to describe the experimental data on the separation of proteins on different chromatographic systems. Using phenomenological parameters, i.e., effective adsorption energies of amino acid residues, we predict the effect of the sequence of these residues in the chain on retention times of proteins for reversed phases of different types (C₄, C₈, C₁₈) in the gradient of a water-acetonitrile binary solvent. It is shown that, in general, the BioLCCC model correctly represents experimental data on the separation of proteins and makes it possible to quantitatively determine the effect of the sequence of amino acid residues on the separation. We show the limits of applicability of the model and explain the universal linear dependence that relates the retention volume and the logarithm of chain length that is observed in the chromatography of peptides and proteins.