Mass Spectrometry-Based Proteomic Profiling of a Silvaner White Wine

Abstract

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.

Keywords: Silvaner; Vitis vinifera; mass spectrometry; proteins; proteomics; wine.

Figure 1

Illustrative scheme of the methods applied for the isolation and identification of proteins from a Silvaner wine. After fractionation via size exclusion chromatography (SEC), the wine proteins were subjected to distinct methods of digestion: (a) in-solution, in which the samples were directly tryptically digested and submitted to LC-MS analyses after the SEC fractionation step; and (b) in-gel, whereby the proteins were further fractionated by SDS-PAGE and then tryptically digested prior to the LC-MS analysis.

Figure 2

(a) SEC chromatogram of proteins from a Silvaner wine (separated according to molecular mass). (b) SDS-PAGE profile of the four main protein fractions obtained from the SEC chromatographic step shown in (a). Some of the identified proteins (sorted by molecular mass) are described in (b).

Figure 3

Venn diagrams presenting the number of characterized (a) and uncharacterized (b) proteins identified after in-gel or in-solution digestion.

Figure 4

(a) Stack-bar blot of the percentage distribution of the found protein to the organisms (b) Quantitative comparison of the identified proteins from a Silvaner wine divided per cellular function. The number of proteins identified by each digestion technique is also presented. PTM means post-translational modifications.