Application of semiquantitative proteomics techniques to the maillard reaction

Maillard reaction products derived from food protein-derived peptides: insights into flavor and bioactivity

Food protein-derived peptides serve as food ingredients that can influence flavor and bioactivity of foods. The Maillard reaction plays a crucial role in food processing and storage, and generates a wide range of Maillard reaction products (MRPs) that contribute to flavor and bioactivity of foods. Even though the reactions between proteins and carbohydrates have been extensively investigated, the modifications of food protein-derived peptides and the subsequent impacts on flavor and bioactivity of foods have not been fully elucidated. In this review, the flavor and bioactive properties of food-derived peptides are reviewed. The formation mechanisms with respect to MRPs generated from food protein-derived peptides have been discussed. The state-of-the-art studies on impacts of the Maillard reaction on flavor and bioactivity of food protein-derived peptides are also discussed. In addition, some potential negative effects of MRPs are described.

Non-enzymatic glycation and glycoxidation protein products in foods and diseases: an interconnected, complex scenario fully open to innovative proteomic studies

The Maillard reaction includes a complex network of processes affecting food and biopharmaceutical products; it also occurs in living organisms and has been strictly related to cell aging, to the pathogenesis of several (chronic) diseases, such as diabetes, uremia, cataract, liver cirrhosis and various neurodegenerative pathologies, as well as to peritoneal dialysis treatment. Dozens of compounds are involved in this process, among which a number of protein-adducted derivatives that have been simplistically defined as early, intermediate and advanced glycation end-products. In the last decade, various bottom-up proteomic approaches have been successfully used for the identification of glycation/glycoxidation protein targets as well as for the characterization of the corresponding adducts, including assignment of the modified amino acids. This article provides an updated overview of the mass spectrometry-based procedures developed to this purpose, emphasizing their partial limits with respect to current proteomic approaches for the analysis of other post-translational modifications. These limitations are mainly related to the concomitant sheer diversity, chemical complexity, and variable abundance of the various derivatives to be characterized. Some challenges to scientists are finally proposed for future proteomic investigations to solve main drawbacks in this research field.

The impact of the Maillard reaction on the in vitro proteolytic breakdown of bovine lactoferrin in adults and infants

The impact of the Maillard reaction on proteolysis of the bioactive bovine lactoferrin is comparedin vitrobetween adults and infants for the first time, coupling proteomics to elucidate bioactive peptide formation.

A perspective on the Maillard reaction and the analysis of protein glycation by mass spectrometry: probing the pathogenesis of chronic disease

The Maillard reaction, starting from the glycation of protein and progressing to the formation of advanced glycation end-products (AGEs), is implicated in the development of complications of diabetes mellitus, as well as in the pathogenesis of cardiovascular, renal, and neurodegenerative diseases. In this perspective review, we provide an overview on the relevance of the Maillard reaction in the pathogenesis of chronic disease and discuss traditional approaches and recent developments in the analysis of glycated proteins by mass spectrometry. We propose that proteomics approaches, particularly bottom-up proteomics, will play a significant role in analyses of clinical samples leading to the identification of new markers of disease development and progression.

Mass spectrometry to detect the site specificity of advanced glycation/lipoxidation end-product formation on protein: some challenges and solutions

Formation of AGEs (advanced glycation end-products) and ALEs (advanced lipoxidation end-products) on proteins is associated with aging and various diseases of oxidative stress, notably diabetes and its complications. Modification of protein to AGE/ALEs is known to be site-directed and this has potential implications for protein functionality and design of AGE/ALE inhibitors. Determination of the site-specificity of modification is achieved most efficiently by MS. The present paper summarizes some of the challenges that need to be addressed when determining the site-specificity of AGE/ALE formation on protein by MS, using the protein RNase as an example. The following topics are discussed: formation and significance of AGE/ALEs, location of glycated peptides, enzymic digestion of glycated peptides and selection of mass spectrometric settings of analysis for glycated peptides.

CE: a useful analytical tool for the characterization of Maillard reaction products in foods

The Maillard reaction (MR) is a complex series of nonenzymatic reactions between reducing compounds and amines, amino acids, peptides, or proteins that play an important role in the formation of flavors and colors in foods during processing and storage. Also, the antioxidant properties of some Maillard reaction products (MRP) was an additional benefit reported. On the other hand, these reactions decrease the nutritional quality of foods and may result in the formation of toxic MRP. Although, research to assess the risks and benefits associated with the consumption of MRP in the diet is still awaiting for new analytical methodologies to be developed. Structural characterization of MRP has been very challenging due to the chemical diversity of these compounds which present a wide range of polarities and molecular weights, making analyses difficult. CE is a technique that has gained popularity for the separation of complex mixtures that have otherwise proved difficult to analyze. Thus, the purpose of this overview is to give the reader an appreciation of some of the CE analytical developments on the analysis of MRP in model systems and foods, and to address the potential of CE on the characterization of this complex group of compounds.

Enrichment and analysis of nonenzymatically glycated peptides: boronate affinity chromatography coupled with electron-transfer dissociation mass spectrometry

Nonenzymatic glycation of peptides and proteins by d-glucose has important implications in the pathogenesis of diabetes mellitus, particularly in the development of diabetic complications. However, no effective high-throughput methods exist for identifying proteins containing this low-abundance post-translational modification in bottom-up proteomic studies. In this report, phenylboronate affinity chromatography was used in a two-step enrichment scheme to selectively isolate first glycated proteins and then glycated, tryptic peptides from human serum glycated in vitro. Enriched peptides were subsequently analyzed by alternating electron-transfer dissociation (ETD) and collision induced dissociation (CID) tandem mass spectrometry. ETD fragmentation mode permitted identification of a significantly higher number of glycated peptides (87.6% of all identified peptides) versus CID mode (17.0% of all identified peptides), when utilizing enrichment on first the protein and then the peptide level. This study illustrates that phenylboronate affinity chromatography coupled with LC-MS/MS and using ETD as the fragmentation mode is an efficient approach for analysis of glycated proteins and may have broad application in studies of diabetes mellitus.

Application of electron transfer dissociation mass spectrometry in analyses of non-enzymatically glycated peptides

Non-enzymatic glycation of peptides and proteins by D-glucose has important implications in the pathogenesis of diabetes mellitus, particularly in the context of development of diabetic complications. The fragmentation behavior of glycated peptides produced from reaction of D-glucose with lysine residues was investigated by electron transfer dissociation (ETD) and collision-induced dissociation (CID) tandem mass spectrometry. It was found that high abundance ions corresponding to various degrees of neutral water losses, as well as furylium ion production, dominate the CID spectra, and that the sequence-informative b and y ions were rarely observed when Amadori-modified peptides were fragmented. Contrary to what was observed under CID conditions, ions corresponding to neutral losses of water or furylium ion production were not observed in the ETD spectra. Instead, abundant and almost complete series of c- and z-type ions were observed regardless of whether the modification site was located in the middle of the sequence or close to the N-terminus, greatly facilitating the peptide sequencing. This study strongly suggests that ETD is a better technique for proteomic studies of non-enzymatically glycated peptides and proteins.