Enzymatic hydrolysis of thermo-sensitive grape proteins by a yeast protease as revealed by a proteomic approach

- Enzymatic hydrolysis of grape proteins by an extracellular yeast protease
- Identification of the hydrolyzed grape proteins as PR proteins
- Likely application in the wine making process against wine proteic haze

Grape juice protein hydrolysis can be proposed as one of the potential alternative methods to prevent haze wine formation. Saccharomyces cerevisiae PlR1 is a wild yeast strain of grapes able to secrete an acidic proteolytic activity during growth on a synthetic medium with proline. The aim of the present work was to confirm, by SDS-PAGE and two-dimensional electrophoresis (2D-E), the hydrolysis of some grape juice proteins after incubation with a S. cerevisiae PlR1 culture supernatant, and then to identify these hydrolyzed proteins by nano-LC-MS/MS analysis. Results obtained showed that hydrolyzed proteins correspond to pathogenesis-related (PR) proteins, in particular, thaumatin-like (TL) proteins and chitinases. Some of these PR proteins are likely to be implicated in the wine haze formation. These proteins will be isolated and characterized in order to explain why they are sensitive to enzymatic hydrolysis. Otherwise, the protease will be purified, sequenced and cloned in yeast in order to improve the wine stability with regard to proteic haze.