Thermochemical characteristics of some glycylpeptides interaction with anionic micelles in a phosphate-buffered saline solution of sodium dodecyl sulfate

Abstract

The dissolution enthalpies of glycylglycine (GlyGly), glycylglycylglycine (GlyGlyGly) and glycyl-L-tyrosine (GlyTyr) in phosphate-buffered saline solution and micellar solution (sodium dodecyl sulfate (SDS) + phosphate-buffered saline solution) were measured calorimetrically at pH = 7.4 and T = 298.15 K. The thermochemical characteristics of the interaction of peptides with micelles are defined as the transfer enthalpies of peptides into a micellar solution of sodium dodecyl sulfate in a phosphate-buffered saline solution. A comparison of the obtained results revealed the influence of the ionic state, chain length and hydrophobicity of peptides on the characteristics of their interaction with anionic micelles. The effect of micelle contraction upon interaction with peptide zwitterions was found. The differences in the dissolution enthalpies in the buffer and in pure water are described by the contributions of acid dissociation of peptides, which is accompanied by a change in the fractions of the zwitter-ionic and anionic forms with a change in pH.