1H NMR Spectroscopy As Tool To Study Transglutaminase Crosslinking Of Pea Globulin

Abstract

Skiathos Island, GREECE - 30 May - 02 June 2013International audienceA new method based on NMR spectroscopy was developed to detect the G-L (GlutamylLysine) isopeptide bonds formed by the enzymatic transglutaminase reaction. Because of thecomplexity of NMR signals of proteins due to their structures, the method was first developedon a model system (glutamine and lysine) to simplify the detection of the G-L residue. Andthen, the results were applied on the real protein matrix (pea globulin). MTG treatment ofmodel system led to the appearance of a new resonance on NMR spectrum which isoriginated probably from the ε-methylene protons of lysine residues covalently linked toglutamine. The comparison between NMR spectra of MTG-treated and untreated pea globulinwith MTG-treated model system permitted to identify the G-L isopeptide signal. The G-Lisopeptide signal is also observed in the NMR spectra of native pea globulin (untreated whichMTG), indicating that the isopeptide is naturally present in pea proteins. However, thesuperimposition of NMR spectra of MTG-treated and untreated pea globulin shows a higherintensity of G-L isopeptide signal for MTG-treated samples. The increased signal intensityevidences the enzymatic reaction and permits to quantify the G-L isopeptide