The Effect of Dephosphorylation on the Conformation of Peptides from β-Casein

Abstract

Peptides β(1-28) and β(1-52) incorporating residues 1-28 and 1-52 of β-casein were prepared by proteolysis of the protein using plasmin and chymotrypsin respectively. Analysis of the circular dichroism spectra of the isolated peptides revealed that limited levels of α-helix were formed only by peptide β(1-52) and then only in the presence of >40% trifluoroethanol (TFE). Partial dephosphorylation of the peptides by treatment with alkaline phosphatase resulted in the formation of significant levels of α-helix in both peptides in the presence of TFE. However, no α-helix was detected in either peptide in the absence of TFE.