Blue native/SDS-PAGE combined with iTRAQ analysis reveals advanced glycation end-product-induced changes of synaptosome proteins in C57 BL/6 mice

Maillard Proteomics: Opening New Pages

Protein glycation is a ubiquitous non-enzymatic post-translational modification, formed by reaction of protein amino and guanidino groups with carbonyl compounds, presumably reducing sugars and α-dicarbonyls. Resulting advanced glycation end products (AGEs) represent a highly heterogeneous group of compounds, deleterious in mammals due to their pro-inflammatory effect, and impact in pathogenesis of diabetes mellitus, Alzheimer's disease and ageing. The body of information on the mechanisms and pathways of AGE formation, acquired during the last decades, clearly indicates a certain site-specificity of glycation. It makes characterization of individual glycation sites a critical pre-requisite for understanding in vivo mechanisms of AGE formation and developing adequate nutritional and therapeutic approaches to reduce it in humans. In this context, proteomics is the methodology of choice to address site-specific molecular changes related to protein glycation. Therefore, here we summarize the methods of Maillard proteomics, specifically focusing on the techniques providing comprehensive structural and quantitative characterization of glycated proteome. Further, we address the novel break-through areas, recently established in the field of Maillard research, i.e., in vitro models based on synthetic peptides, site-based diagnostics of metabolism-related diseases (e.g., diabetes mellitus), proteomics of anti-glycative defense, and dynamics of plant glycated proteome during ageing and response to environmental stress.

Secretome analysis of Pleurotus eryngii reveals enzymatic composition for ramie stalk degradation

Pleurotus eryngii (P. eryngii) can secrete large amount of hydrolytic and oxidative enzymes to degrade lignocellulosic biomass. In spite of several researches on the individual lignolytic enzymes, a direct deconstruction of lignocellulose by enzyme mixture is not yet possible. Identifying more high-performance enzymes or enzyme complexes will lead to efficient in vitro lignocelluloses degradation. In this report, secretomic analysis was used to search for the new or interesting enzymes for lignocellulose degradation. Besides, the utilization ability of P. eryngii to ramie stalk substrate was evaluated from the degradation of cellulose, hemicellulose, and lignin in medium and six extracellular enzymes activities during different growth stages were discussed. The results showed that a high biological efficiency of 71% was obtained; cellulose, hemicelluloses, and lignin decomposition rates of P. eryngii were 29.2, 26.0, and 51.2%, respectively. Enzyme activity showed that carboxymethyl cellulase, xylanase, laccase, and peroxidase activity peaks appeared at the primordial initiation stage. In addition, we profiled a global view of the secretome of P. eryngii cultivated in ramie stalk media to understand the mechanism behind lignocellulosic biomass hydrolysis. Eighty-seven nonredundant proteins were identified and a diverse group of enzymes, including cellulases, hemicellulases, pectinase, ligninase, protease, peptidases, and phosphatase implicated in lignocellulose degradation were found. In conclusion, the information in this report will be helpful to better understand the lignocelluloses degradation mechanisms of P. eryngii.

Recent advances in quantitative neuroproteomics

The field of proteomics is undergoing rapid development in a number of different areas including improvements in mass spectrometric platforms, peptide identification algorithms and bioinformatics. In particular, new and/or improved approaches have established robust methods that not only allow for in-depth and accurate peptide and protein identification and modification, but also allow for sensitive measurement of relative or absolute quantitation. These methods are beginning to be applied to the area of neuroproteomics, but the central nervous system poses many specific challenges in terms of quantitative proteomics, given the large number of different neuronal cell types that are intermixed and that exhibit distinct patterns of gene and protein expression. This review highlights the recent advances that have been made in quantitative neuroproteomics, with a focus on work published over the last five years that applies emerging methods to normal brain function as well as to various neuropsychiatric disorders including schizophrenia and drug addiction as well as of neurodegenerative diseases including Parkinson's disease and Alzheimer's disease. While older methods such as two-dimensional polyacrylamide electrophoresis continued to be used, a variety of more in-depth MS-based approaches including both label (ICAT, iTRAQ, TMT, SILAC, SILAM), label-free (label-free, MRM, SWATH) and absolute quantification methods, are rapidly being applied to neurobiological investigations of normal and diseased brain tissue as well as of cerebrospinal fluid (CSF). While the biological implications of many of these studies remain to be clearly established, that there is a clear need for standardization of experimental design and data analysis, and that the analysis of protein changes in specific neuronal cell types in the central nervous system remains a serious challenge, it appears that the quality and depth of the more recent quantitative proteomics studies is beginning to shed light on a number of aspects of neuroscience that relates to normal brain function as well as of the changes in protein expression and regulation that occurs in neuropsychiatric and neurodegenerative disorders.