Comparison of Non-covalent Interactions Between a Series of N-Phosphoryl Dipeptide or Methyl Esters and Protein by Electrospray Ionization Mass Spectrometry

The non-covalent interaction between a series of N-phosphoryl dipeptides (or methyl esters) (DPP) and protein was studied by ESI-MS and UV–vis spectrometer. The function of different groups in DPP and binding sites of protein were investigated. The results revealed that hydroxyl and aromatic ring in DPP were both important group for the interaction, and aromatic ring had double functions on the interaction. In addition, the molecular size, flexibility and steric hindrance showed obvious effects on the interaction, while, the chirality, sequence and length of carbon chains (changing 1–2C) of amino acid residue in DPP showed little effects on the interaction under the experimental conditions. Phosphoryl oligopeptides having extended structure, good molecular flexibility and smaller spatial hindrance could contract the protein conformation in solution. The aromatic, basic, acid and amide amino acid residues of protein may be the main binding sites and contributed to the survival of the complexes.