title: Characteristics of glycation and glycation sites of lysozyme by matrix-assisted laser desorption/ionization time of flight/time-of-flight mass spectrometry and Liquid chromatography-electrospray ionization tandem mass spectrometry.
abstract: Protein glycation with reducing sugars through the Maillard reaction is regarded as one of the most important reactions in food chem- istry. Amadori rearrangement products [ARPs] are produced at the initial stage of the Maillard reaction and then advanced glycation products may be formed. We report here that using matrix-assisted laser desorption/ionization mass spectrometry with time-of-flight detection [MALDI-TOF-MS] and electrospray ionization mass spectrometry (ESI-MSJ to monitor the glycation process in lysozyme and the D-glucose model system. MALDI-TOF-MS displayed a heterogeneous distribution of glycation via a total mass shift in spectra. However electrospray ionization mass spectrometry [ESI-MS] data showed that a total of four molecules of glucose reacted with Lysozyme at an increase in molecular weight by a 162 Da unit. Further, we identified the glycation sites of lysozyme by using MALDI-TOF/TOF-MS and Liquid chromatography [LC]-ESI-MS/MS. Besides the two glycation sites of Lys1 and Lys97 identified by MALDI-TOF/TOF-MS, the other two glycation sites of Lys13 and Lys116 were characterized unambiguously by LC-ESI-MS/MS. Both MALDI-TOF/TOF-MS and LC-ESI-MS/ MS provided confidence in the study of the glycation by restricting the number of possible residues through (un]modified ions. The study is useful to monitor and characterize glycation in protein systems based on both MALDI-TOF-MS and ESI-MS. Comparatively, LC-ESI-MS/MS provides more fragments with better recovery for the identification of glycation than MALDI-TOF/TOF-MS.
authors.forename: Eric Dongliang
authors.initials: ED
authors.lastname: Ruan
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Ruan
authors.forename: Manuel
authors.initials: M
authors.lastname: Juáreza
mesh_terms: D000595:Amino Acid Sequence; D002853:Chromatography, Liquid / Q000379:methods*; D006031:Glycosylation; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D009113:Muramidase