MS based proteomic approaches for analysis of barley malt

New criteria for the molecular identification of cereal grains associated with archaeological artefacts

The domestication and transmission of cereals is one of the most fundamental components of early farming, but direct evidence of their use in early culinary practices and economies has remained frustratingly elusive. Using analysis of a well-preserved Early Bronze Age wooden container from Switzerland, we propose novel criteria for the identification of cereal residues. Using gas chromatography mass spectrometry (GC-MS), we identified compounds typically associated with plant products, including a series of phenolic lipids (alkylresorcinols) found only at appreciable concentration in wheat and rye bran. The value of these lipids as cereal grain biomarkers were independently corroborated by the presence of macrobotanical remains embedded in the deposit, and wheat and rye endosperm peptides extracted from residue. These findings demonstrate the utility of a lipid-based biomarker for wheat and rye bran and offer a methodological template for future investigations of wider range of archaeological contexts. Alkylresorcinols provide a new tool for residue analysis which can help explore the spread and exploitation of cereal grains, a fundamental component of the advent and spread of farming.

Study of quantitative changes of cereal allergenic proteins after food processing

BACKGROUND

Within last few years, the occurrence of food allergens and corresponding food allergies has been increasing, therefore research into the individual allergens is required. In the present work, the effect of cereal processing on the amounts of allergenic proteins is studied by modern proteomic-based approaches. The most important wheat and barley allergens are low-molecular-weight (LMW) proteins. Therefore we investigated the relative quantitative changes of these proteins after food technological processing, namely wheat couscous production and barley malting.

RESULTS

A comparative study using mass spectrometry in connection with the technique of isobaric tag for relative and absolute quantification (iTRAQ) revealed that the amount of wheat allergenic LMW proteins decreased significantly during couscous production (approximately to 5-26% of their initial content in wheat flour). After barley malting, the amounts of the majority of LMW proteins decreased as well, although to a lesser extent than in the case of wheat/couscous. The level of two allergens even slightly increased.

CONCLUSION

Suggested proteomic strategy proved as universal and sensitive method for fast and reliable identification of various cereal allergens and monitoring of their quantitative changes during food processing. Such information is important for consumers who suffer from allergies.

Expanding resolution of metalloprotein separations from soybean seeds using 2D-HPLC-ICP-MS and SDS-PAGE as a third dimension

This work reports on the use of a three dimensional separation system to enhance metalloprotein information when considering soybean seeds. Separations using size exclusion chromatography (SEC) allowed identification of three metal fractions. Following an anion exchange (AEX) chromatographic separation in the second dimension, the resultant sub-fractions were lyophilized and subjected to a third dimension of separation using a polyacrylamide gel electrophoresis (SDS-PAGE). After the separation, the bands were digested, and, in addition to others, the following proteins, previously associated with metals, were identified: 3-lipoxygenase A chain (soybean) complex with 13(S)-hydroperoxy-9(Z),11(E)-octadecadienoic acid, beta-amylase [Glycine max], seed lipoxygenase-1, lipoxygenase [G. max], seed lipoxygenase-2 (Pisum sativum) and beta-conglycinin.

BIOLOGICAL SIGNIFICANCE

Techniques presenting high resolution are desired due to their capability in resolving great amount of signals (responses) generated from hundreds of proteins generally found in different samples. To the best of our knowledge, this is the first time that bidimensional chromatographic system which allied to another separation dimension is applied for improving protein identification, so that higher number and different proteins were found when comparing 2D dimension with 3D dimension. In fact, this strategy is welcoming in proteomics studies, in order to improve the comprehension of those systems that present large number of proteins. This article is part of a Special Issue entitled: Environmental and structural proteomics.

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.