Analysis of protein composition of red wine in comparison with rosé and white wines by electrophoresis and high-pressure liquid chromatography-mass spectrometry (HPLC-MS)

Mass Spectrometry-Based Proteomic Profiling of a Silvaner White Wine

The comprehensive identification of the proteome content from a white wine (cv. Silvaner) is described here for the first time. The wine protein composition isolated from a representative wine sample (250 L) was identified via mass spectrometry (MS)-based proteomics following in-solution and in-gel digestion methods after being submitted to size exclusion chromatographic (SEC) fractionation to gain a comprehensive insight into proteins that survive the vinification processes. In total, we identified 154 characterized (with described functional information) or so far uncharacterized proteins, mainly from Vitis vinifera L. and Saccharomyces cerevisiae. With the complementarity of the two-step purification, the digestion techniques and the high-resolution (HR)-MS analyses provided a high-score identification of proteins from low to high abundance. These proteins can be valuable for future authentication of wines by tracing proteins derived from a specific cultivar or winemaking process. The proteomics approach presented herein may also be generally helpful to understand which proteins are important for the organoleptic properties and stability of wines.

Haze Formation and the Challenges for Peptidases in Wine Protein Fining

To meet consumer expectations, white wines must be clear and stable against haze formation. Temperature variations during transport and storage may induce protein aggregation, mainly caused by thaumatin like-proteins (TLPs) and chitinases (CHIs), which thus need to be fined before bottling of the wine. Currently, bentonite clay is employed to inhibit or minimize haze formation in wines. Alternatively, peptidases have emerged as an option for the removal of these thermolabile proteins, although their efficacy under winemaking conditions has not yet been fully demonstrated. The simultaneous understanding of the chemistry behind the cleavage of haze proteins and the haze formation may orchestrate alternative methods of technological and economic importance in winemaking. Therefore, we provide an overview of wine fining by peptidases, and new perspectives are developed to reopen discussions on the aforementioned challenges.

The Secondary Structure of a Major Wine Protein is Modified upon Interaction with Polyphenols

Polyphenols are an important constituent of wines and they are largely studied due to their antioxidant properties and for their effects on wine quality and stability, which is also related to their capacity to bind to proteins. The effects of some selected polyphenols, including procyanidins B1 and B2, tannic acid, quercetin, and rutin, as well as those of a total white wine procyanidin extract on the conformational properties of the major wine protein VVTL1 (Vitis vinifera Thaumatin-Like-1) were investigated by Synchrotron Radiation Circular Dichroism (SRCD). Results showed that VVTL1 interacts with polyphenols as demonstrated by the changes in the secondary (far-UV) and tertiary (near-UV) structures, which were differently affected by different polyphenols. Additionally, polyphenols modified the two melting temperatures (TM) that were found for VVTL1 (32.2 °C and 53.9 °C for the protein alone). The circular dichroism (CD) spectra in the near-UV region revealed an involvement of the aromatic side-chains of the protein in the interaction with phenolics. The data demonstrate the existence of an interaction between polyphenols and VVTL1, which results in modification of its thermal and UV denaturation pattern. This information can be useful in understanding the behavior of wine proteins in presence of polyphenols, thus giving new insights on the phenomena that are involved in wine stability.

High-proline proteins in experimental hazy white wine produced from partially botrytized grapes

Undesirable effects of the pathogen Botrytis cinerea include reduced quality and quantity of wine grapes. Winemaking is also complicated by the formation of a protein haze in white wines and oxidative browning of red wines. We analyzed proteins in experimental Moravian white wines characterized by their instability and haze formation in bottles during storage despite prior bentonite treatment. To study the relationship of wine proteins and haze, we carried out proteomics on hazy and clear white wines produced with partly or largely botrytized grapes and standard reference wines. Wine proteins were identified after their extraction, electrophoresis, and tryptic digestion by reversed-phase liquid chromatography of peptides, coupled with tandem mass spectrometry. Plant defense proteins, yeast glycoproteins, and various enzymes from Botrytis, particularly hydrolases, were found. As the content of the known haze-active thaumatin-like proteins and chitinases was visually low on stained gels (missing bands) compared to previous studies with unfined wines, other proteins are discussed in terms of the haze formation. As the main novelty, this work reveals the role of high proline-containing proteins in the propensity of white wines to turbidity following prior Botrytis damage of grapes.

Dual role of the RNA helicase DDX5 in post-transcriptional regulation of Myelin Basic Protein in oligodendrocytes

In the central nervous system, oligodendroglial expression of Myelin Basic Protein (MBP) is crucial for the assembly and structure of the myelin sheath. MBP synthesis is tightly regulated in space and time, particularly on the post-transcriptional level. We have identified the DEAD-box RNA helicase DDX5 (alias p68) in a complex with Mbp mRNA in oligodendroglial cells. Expression of DDX5 is highest in progenitor cells and immature oligodendrocytes, where it localizes to heterogeneous populations of cytoplasmic ribonucleoprotein (RNP) complexes associated with Mbp mRNA in the cell body and processes. Manipulation of DDX5 protein amounts inversely affects levels of MBP protein. We present evidence that DDX5 is involved in post-transcriptional regulation of MBP protein synthesis, with implications for oligodendroglial development. In addition, DDX5 knockdown results in an increased abundance of MBP exon 2-positive isoforms in immature oligodendrocytes, most likely by regulating alternative splicing of Mbp. Our findings contribute to the understanding of the complex nature of MBP post-transcriptional control in immature oligodendrocytes where DDX5 appears to affect the abundance of MBP proteins via distinct but converging mechanisms.

Proteomic profiling of German Dornfelder grape berries using data-independent acquisition

Grapevine is one of the most important fruit plants throughout the world. Sequencing of the grape genome in 2007 enabled in-depth analyses of the grape proteome. Whereas many studies addressed changes in proteomic composition of grapes during ripening, we focused on the proteome of mature grape berries from Dornfelder, a characteristic red wine grape for Germany. Current data-independent acquisition proteomics technology enables the analysis of proteomic compositions in a degree of accuracy that was unreachable only a few years ago. Using a label-free proteomics approach, we quantified 712 proteins in mature Dornfelder grape berries, of which 650 could be annotated by the Blast2GO software. Besides identification of proteins, our analysis provides protein amounts using the TOP3 absolute quantification approach. Most of the proteins (200) in mature Dornfelder grape berries are involved in stress response. In addition, all glycolytic key enzymes were detected in mature grape berries suggesting that glycolysis is still active, whereas sugar accumulation through gluconeogenesis utilizing malate as substrate seems to play a minor role.

Hen egg white lysozyme is a hidden allergen in Italian commercial ciders

Hen egg white lysozyme (HEWL) is an enzyme used in alcoholic fermentation for its ability to control the growth of Gram-positive and spoilage bacteria, without inhibiting yeast growth, and it allows a reduction in the use of sulphur dioxide. Nevertheless, considering the potential allergenicity of this protein, the presence of HEWL should be declared on the label of the final product. In this work, we analysed 18 commercial Italian ciders by LC-MS/MS and found traces of HEWL in 12 samples without label declaration. We used Western blot and enzyme-linked immunosorbent assay (ELISA) to verify the immunological activity of HEWL, and to quantify its content in the ciders. Two out of 18 samples were found to be positive both by immunoblot and ELISA. The results indicate the requirement of a more stringent control of commercial ciders and the need of label declaration for ciders treated with such compounds.

A novel preparation technique of red (sparkling) wine for protein analysis

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A new protocol for preparation of proteins in red (sparkling) wine was developed.

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Dialysis, lyophilization, removal of phenolic compounds, protein precipitation.

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New protocol enables improved resolution in subsequent analysis.

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Applicability of the method for other beverages made of grapes is given.

Despite their low concentration, proteins can influence several key enological parameters such as foam stability or haze formation in (sparkling) wine. Most studies focus on white (sparkling) wine since the higher content of phenolic compounds in red wines impairs proteomic research. The aim of the study was the development of a method for the preparation of red (sparkling) wine proteins for proteomic analysis. Three methods of sample preparation were assessed on silver stained SDS-PAGE gels and with MALDI-TOF MS. Our new method was highly suitable for the preparation of proteins for the aforementioned applications. The results showed a substantial increase in signal intensity with a simultaneous decrease in background noise. The preparation protocol consists of (i) dialysis and freeze drying of the sample, (ii) removal of phenolic compounds by water-saturated phenol and (iii) protein precipitation by addition of ammonium acetate. Employment of this method followed by SDS-PAGE analysis allowed for silver stained gels with diminished background or streaking and clearly resolved protein bands. Analysis of spectra obtained from samples prepared according to the proposed protocol showed increased intensity and signal-to-noise ratio in MALDI-TOF MS. Furthermore it was demonstrated that this method can be applied to various kinds of grape products.

Pathogenesis-Related Proteins Limit the Retention of Condensed Tannin Additions to Red Wines

Exogenous additions of condensed tannin (CT) to must or wine are a common winemaking practice, but many studies have reported inexplicably low and variable retention of added CT. We observed that additions of purified CT to red wines can result in the formation of an insoluble precipitate with high nitrogen content. Proteomic analysis of the precipitant identified several classes of pathogenesis-related proteins. Proteins in juices and red wines were quantitated by SDS-PAGE and were highest in native Vitis spp., followed by interspecific hybrids and Vitis vinifera. Wine protein was positively correlated with the ratio of juice protein to the quantity of tannin derived from fruit. The binding of added CT by wine protein could be well modeled by the Freundlich equation. These observations may explain the poor CT retention in previous studies, particularly for interspecific hybrids, and also indicate that protein removal during winemaking may improve exogenous CT retention.

The biochemical basis and clinical evidence of food allergy due to lipid transfer proteins: a comprehensive review

Plant lipid transfer proteins (LTPs) are ubiquitous proteins that are found in divergent plant species. Although the exact function of LTPs is not fully understood, LTPs are conserved across a broad range of plant species. Because LTPs share structural features, there is an increased probability for significant allergic cross-reactivity. The molecular features of LTPs also decrease the probability of degradation due to cooking or digestion, thereby increasing the probability of systemic absorption and severe allergic reactions. LTP allergy, unlike other forms of anaphylaxis, tends to occur more frequently in areas of lower latitude. The geographic distribution of LTP allergy, along with evidence of increased sensitization after respiratory exposure, has led to the hypothesis that LTP-related food allergy may be secondary to sensitization via the respiratory route. Clinical reactions associated with LTPs have broad clinical phenotypes and can be severe in nature. Life-threatening clinical reactions have been associated with ingestion of a multitude of plant products. Component-resolved diagnosis has played a significant role in research applications for LTP allergy. In the future, component-resolved diagnosis may play a significant role in day-to-day clinical care. Also, quantitative analysis of LTPs in foodstuffs may allow for the identification and/or production of low-LTP foods, thereby decreasing the risk to patients with LTP allergy. Furthermore, sublingual immunotherapy may provide a therapeutic option for patients with LTP allergy.

Characterization of a grape class IV chitinase

A chitinase was purified from Vitis vinifera Manzoni Bianco grape juice and characterized. On the basis of proteomic analysis of tryptic peptides, a significant match identified the enzyme as a type IV grape chitinase previously found in juices of other V. vinifera varieties. The optimal pH and temperature for activity toward colloidal chitin were found to be 6 and 30 °C, respectively. The enzyme was found to hydrolyze chitin and oligomers of N-acetylglucosamine, generating N,N'-diacetylchitobiose and N-acetylglucosamine as products, but was inactive toward N,N'-diacetylchitobiose. The enzyme exhibited both endo- and exochitinase activities. Because yeast contains a small amount of chitin in the cell wall, the possibility of growth inhibition was tested. At a concentration and pH expected in ripe grapes, no inhibition of wine yeast growth by the chitinase was observed.

It's time to pop a cork on champagne's proteome!

Champagne is a world-renowned French sparkling wine, which undergoes many steps (fermentation, aging …) for its elaboration. Various compounds might evolve during this winemaking process and thus modify its final quality. Here, we report the first proteome analysis of two standard commercial Champagne wines, using the powerful Combinatorial Peptide Ligand Library (CPLL) technique. Indeed, wine proteins are present in small amounts but they are key compounds, likely to impact on both foam quality and aroma behavior. Forty-three unique gene products were retrieved in a single-varietal champagne and a blended champagne. Several proteins from Vitis vinifera together with seven yeast proteins were undoubtedly identified in these Champagne wines.

BIOLOGICAL SIGNIFICANCE

The main advantage of CPLLs was the detection of low abundance proteins despite the absence of purification or pre-concentration step. It is an important fact to take into account, since Champagne wines generally contain a low amount of proteins (5-10mg/L) that implies to usually concentrate wine proteins before 1D or 2D electrophoresis. Most Champagne proteins are grape and yeast glycoproteins which are considered as good foam "promoters". Some of these proteins might also interact with wine aromas, and thus contribute to the overall quality of Champagne wines. This article is part of a Special Issue entitled: Proteomics of non-model organisms.

Mass Spectrometry-based Quantification of Proteins and Peptides in Food

The application of quantitative proteomics to food analysis is in its infancy. This is partly due to the diverse range of plant and animal species consumed as foods, many of which are not sequenced, making annotation of food proteomes difficult. In addition food processing procedures and interactions with other food components, such as lipids and starch, introduce a diverse range of chemical and conformational changes to proteins, many of which are poorly defined. Mass spectrometry-based molecular profiling has great potential as quality assurance tool for food authenticity and traceability, safety and quality. A driver for the application of quantitative protein mass spectrometry-based methods to food has been the need to develop confirmatory methods for allergen analysis in support of food allergen labelling regulations. In addition to providing rigorous quantitative methodology for complex biomacromolecules, protein mass spectrometry is also allowing us, for the first time, to discover how processing procedures modify the foods we eat at a molecular level. Such knowledge is essential if we are to understand how food processing can be used to optimise the beneficial health effects of foods.

Precipitation of champagne base wine proteins prior to 2D electrophoresis

Numerous methods have been employed to depict the protein content of wines. Among them, two-dimensional electrophoresis (2D-E) presents a powerful resolution, but has been poorly applied to wine. Furthermore, 2D-E was coupled with various extraction methods of proteins without any reference method for wine. Here, we describe a rapid method to extract proteins from a champagne base wine through ultrafiltration followed by precipitation with ethanol and trichloroacetic acid. More than 50 spots were visualized on 2D-gels (7 cm, pH 3-6) by colloidal Coomassie Brilliant Blue staining.

Acetylcholine-binding protein in the hemolymph of the planorbid snail Biomphalaria glabrata is a pentagonal dodecahedron (60 subunits)

Nicotinic acetylcholine receptors (nAChR) play important neurophysiological roles and are of considerable medical relevance. They have been studied extensively, greatly facilitated by the gastropod acetylcholine-binding proteins (AChBP) which represent soluble structural and functional homologues of the ligand-binding domain of nAChR. All these proteins are ring-like pentamers. Here we report that AChBP exists in the hemolymph of the planorbid snail Biomphalaria glabrata (vector of the schistosomiasis parasite) as a regular pentagonal dodecahedron, 22 nm in diameter (12 pentamers, 60 active sites). We sequenced and recombinantly expressed two ∼25 kDa polypeptides (BgAChBP1 and BgAChBP2) with a specific active site, N-glycan site and disulfide bridge variation. We also provide the exon/intron structures. Recombinant BgAChBP1 formed pentamers and dodecahedra, recombinant BgAChBP2 formed pentamers and probably disulfide-bridged di-pentamers, but not dodecahedra. Three-dimensional electron cryo-microscopy (3D-EM) yielded a 3D reconstruction of the dodecahedron with a resolution of 6 Å. Homology models of the pentamers docked to the 6 Å structure revealed opportunities for chemical bonding at the inter-pentamer interfaces. Definition of the ligand-binding pocket and the gating C-loop in the 6 Å structure suggests that 3D-EM might lead to the identification of functional states in the BgAChBP dodecahedron.

U-2012: An improved Lowry protein assay, insensitive to sample color, offering reagent stability and enhanced sensitivity

Traditional colorimetric protein assays such as Biuret, Lowry, and modified Lowry (U-1988) are unsuitable for colored biological samples. Here we describe an improved Lowry protein assay (U-2012), which utilizes stable reagents and offers enhanced sensitivity over the U-1988 assay. U-2012 circumvents interference from colored pigments and other substances (for example sugars) bound to perchloric acid (PCA) precipitated proteins by hydrogen peroxide (H2O2) induced oxidation at 50°C. Unused hydrogen peroxide is neutralized with sodium pyruvate before protein estimation for a stable end color. The U-2012 assay is carried out on the PCA precipitated protein pellet after neutralization (with Na2CO3 plus NaOH), solubilization (in Triton-NaCl), decolorization (by H2O2) and pyruvate treatment. Protein contents in red wine and homogenates of beetroot and blueberry are calculated from standard curves established for various proteins and generated using a rectangular hyperbola with parameters estimated with Microsoft Excel's Solver add-in. The U-2012 protein assay represents an improvement over U-1988 and gives a more accurate estimation of protein content.

Prevalence of wine intolerance: results of a survey from Mainz, Germany

BACKGROUND

Wine is an ancient food product, ubiquitous across cultures all over the world. Its effects on health have been extensively studied, yet there have been only a few case reports of wine intolerance or wine allergy. We studied the prevalence of self-reported wine intolerance in the adult population of Mainz, Germany.

METHODS

In 2010, a questionnaire-based cross-sectional study was conducted to assess the prevalence of wine intolerance among adults in Mainz, a city in the wine-cultivating area of Rhine-Hesse. 4000 persons randomly chosen from population lists were asked to fill out a questionnaire about their alcohol intake and the occurrence of various intolerance reactions and allergy-like symptoms after drinking wine.

RESULTS

Of the 4000 who received the questionnaire, 948 (23.7%) filled it out and returned it to us. 68 (7.2% of respondents) reported intolerance to wine and/or allergy-like symptoms after drinking wine. Self-reported wine intolerance was more prevalent in women than in men (8.9% vs. 5.2%, p = 0.026). Wine-intolerant persons also more commonly reported intolerance to beer and alcohol in general. Allergy-like symptoms were more common after the consumption of red wine. The most commonly reported reactions to wine were cutaneous flushing, itch, and nasal congestion.

CONCLUSION

Wine intolerance was found to be more common than expected. The data reported here are less suggestive of an immunologically mediated allergy than of intolerance to alcohol, biogenic amines, or other ingredients of wine.

Quantitative colorimetric assay for total protein applied to the red wine Pinot noir

A standard method for assaying protein in red wine is currently lacking. The method described here is based on protein precipitation followed by dye binding quantification. Improvements over existing approaches include minimal sample processing prior to protein precipitation with cold trichloroacetic acid/acetone and quantification based on absorbance relative to a commercially available standard representative of proteins likely to be found in wine, the yeast mannoprotein invertase. The precipitation method shortened preparation time relative to currently published methods and the mannoprotein standard yielded values comparable to those obtained by micro-Kjeldahl analysis. The assay was used to measure protein in 48 Pinot noir wines from 6 to 32 years old. The protein content of these wines was found to range from 50 to 102 mg/L with a mean value of 70 mg/L. The availability of a simple and relatively rapid procedure for assaying protein provides a practical tool to quantify a wine component that has been overlooked in routine analyses of red wines.

Immunochemical and mass spectrometry detection of residual proteins in gluten fined red wine

Recently, wheat gluten has been proposed as technological adjuvant in order to clarify wines. However, the possibility that residual gluten proteins remain in treated wines cannot be excluded, representing a hazard for wheat allergic or celiac disease patients. In this work, commercial wheat glutens, in both partially hydrolyzed (GBS-P51) and nonhydrolyzed (Gluvital 21000) forms, were used as fining agents in red wine at different concentrations. Beside immunoenzymatic analyses using anti-gliadin, anti-prolamin antibodies and pooled sera of wheat allergic patients, a method based on liquid chromatography coupled to mass spectrometry has been proposed to detect residues of gluten proteins. Residual gluten proteins were detected by anti-prolamin antibodies, anti-gliadin antibodies and sera-IgE only in the wine treated with GBS-P51 at concentration 50, 150, and 300 g/hL, respectively, whereas no residual proteins were detected by these systems in the wine treated with Gluvital 21000. In contrast liquid chromatography-mass spectrometry analyses allowed the detection of proteins in red wines fined down to 1 g/hL of Gluvital 21000 and GBS-P51. Our results indicate that MS methods are superior to immunochemical methods in detecting gluten proteins in wines and that adverse reactions against gluten treated wines cannot be excluded.

Noah's nectar: the proteome content of a glass of red wine

Combinatorial peptide ligand libraries (CPLLs) have been adopted for harvesting and identifying traces of proteins present in red wines. Surprisingly, although it is stated that red wines are in general fined with egg albumin, for all Italian wines investigated (in the areas around Chiari and Verona as well as in the Chianti area) we find that the only fining agent used is bovine casein, just like in white wines. Although the typical levels of casein found range between 45 to 85μg/L, in one case as little as 3.8μg/L of casein could be detected, an extremely high level of sensitivity, close to our lower detection limit of 1μg/L reported for white wines. As a result of such treatments, very small amounts of residual proteins in red wines could be identified: essentially no residual grape proteins (except for thaumatin), but only traces of proteins from Saccharomyces cerevisiae and a few proteins from plant pathogens and fungi (e.g., Botryotinia fuckeliana, Sclerotinia sclerotiorum, Aspergillus aculeatus). Contrary to what has been found in white wines, the best capture efficiency with CPLLs has occurred at pH 7.2 and pH 9.3, with minimal capture at pH 3.3. The fact that such very low levels of fining agents can still be detected in treated red wines should be taken into consideration by winemakers in labelling their products and by EC rulers in issuing proper regulations.

Cockroach allergens Per a 3 are oligomers

Allergens from cockroaches cause major asthma-related health problems worldwide. Among them Per a 3 belongs to the most potent allergens. Although the sequences of some members of the Per a 3-family are known, their biochemical and biophysical properties have not been investigated. Here we present for the first time a thorough structural characterization of these allergens, which have recently been tested to induce an increase of allergy specific indicators in blood of Europeans. We isolated two Per a 3 isoforms, which occur freely dissolved in the hemolymph as hexamers with molecular masses of 465+/-25kDa (P II) and 512+/-25kDa (P I). Their sedimentation coefficients (S(20,W)) were determined to be 17.4+/-0.7 S (P II) and 19.0+/-0.9 S (P I), respectively. Sequence analysis revealed that P II consists of two subunit types known as allergens Per a 3.01 and Per a 3.0201, while PI consists of a new allergenic subunit type designated as Per a 3.03. A 3D model of the hexameric allergen Per a 3 was obtained by homology modelling. Almost all of the recently predicted 11 putative antigenic peptides and reported IgE-epitopes could be located on the surface of the hexamer, thus being freely accessible in the hexameric structure of the native molecules. We propose this might contribute to their allergic potential as well as their extreme stability with respect to temperature.

Heard it through the grapevine: proteomic perspective on grape and wine

Grapevine (Vitis ssp.) is currently considered as the most important fruit plant throughout the world, both due to its economic importance and to its role as a non climacteric model species. The relevance of the studies devoted to the dissection of grapevine biology and biochemistry underlines the great amount of attention that this plant has attracted over the last decade. The milestones among these studies are represented by the accomplishment of the genome sequencing programmes in 2007 [1,2]. Since then, the investigation of grape OMICS has been implemented, and the number of reports published on grape and wine protein investigations using proteomic techniques have significantly improved knowledge in the field.

Identification of allergenic milk proteins markers in fined white wines by capillary liquid chromatography-electrospray ionization-tandem mass spectrometry

A method based on capillary liquid chromatography combined with electrospray ionization-tandem mass spectrometry (CapLC-ESI-MS-MS) for the detection and identification of casein deriving peptides in fined white wine is described. This is the first step towards the development of a liquid chromatography mass spectrometric method for the detection/identification of markers of potentially allergenic milk proteins used as wine fining agents. The method demonstrated to be capable of detecting some peptides arising from alpha and beta casein (with the relative aminoacidic sequences elucidated) in extracts of white wine fined with casein at 100 and 1000 microg/mL. This MS based approach appears to be a useful tool for screening purposes as well as a confirmatory tool for the unequivocal identification of caseins in ELISA positive samples.