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Kinetic characterization of arginase from Saccharomyces cerevisiae during alcoholic fermentation at different temperatures

Benucci, Ilaria, Fiorelli, Vittorio, Lombardelli, Claudio, Liburdi, Katia, Esti, Marco
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2017 v.82 pp. 268-273
Saccharomyces cerevisiae, alcoholic fermentation, arginase, arginine, catalytic activity, equations, grape juice, grapes, inoculum, temperature, yeasts
The kinetic characterization of arginase activity of a commercial S. cerevisiae strain was carried out for the first time, estimating the kinetic parameters (Vmax, K0.5 and Vmax/K0.5) throughout alcoholic fermentation in order to investigate the catalytic efficiency of the enzyme and its ability in metabolizing arginine to sustain biosynthetic processes. Alcoholic fermentation was carried out at three different temperatures (15, 20, 25 °C) in semi-synthetic grape juice added with arginine at usual maximal concentration (1 g L−1) in grape must.Arginine uptake was quite constant throughout fermentation process and it was more effectively assimilated during high temperature fermentation (20 and 25 °C) than at 15 °C. The sigmoidal behavior of yeast arginase kinetic curves, well fitted to the Hill equation, indicated a mechanism of positive cooperativity for the trimeric enzyme. The highest Vmax (4740.0 U mg−1BSAeq) and the maximal catalytic efficiency (78.87 min−1) were observed when fermentation was at 20 °C approximately 3 days after the inoculum. Moreover, the K0.5 value was similar (53–60 mg mL−1) when maximal catalytic efficiency was achieved, thus indicating that the affinity of enzyme for the substrate is not altered by fermentation temperature which only affected product release velocity and therefore Vmax/K0.5 ratio.