Abstract
Two dimensional NMR spectroscopy was used to study the structure of a peptide composed of the N-terminal 42 amino acid residues of beta-casein. The peptide was obtained by enzymic cleavage using endoproteinase Asp-N. Complete sequence-specific 1H NMR assignment was performed for the peptide at three Ca2+ concentrations (0, 22 and 37 mM). The NMR results show that the peptide was highly flexible and adopted multiple conformations. No stable secondary structures were present; however, the peptide had some regions with non-random structure. The region between residues Leu16 and Asn27 adopted conformations with an increased contribution of alpha-helical structure, a so-called nascent helix. Two regions, Glu11-SerP15 and Lys29-Phe33 showed an increased population of conformations with extended structures. Addition of Ca2+ induced chemical shift changes for the backbone amide protons, especially around the phosphoserine region and around the suggested alpha-helical structure, indicating that the addition of Ca2+ stabilized the structure already present in the apo form of the peptide.
Original language | English |
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Pages (from-to) | 495-506 |
Journal | Journal of Dairy Research |
Volume | 61 |
Issue number | 4 |
DOIs | |
Publication status | Published - 1994 |
MoE publication type | A1 Journal article-refereed |