Thermal denaturation kinetics of yeast proteins in whole cells of Saccharomyces cerevisiae and Kluyveromyces fragilis

摘要

The kinetics of thermal denaturation of yeast proteins in intact cells of Saccharomyces cerevisiae instant dry yeast and Kluyveromyces fragilis L-1930 have been studied through differential scanning calorimetry. Maximum deflection-peak temperatures (T-P) were greater for S. cerevisiae (66.65 degreesC) than for K. fragilis (63.21degrees C). Kinetic parameters showed that the former was slightly more resistant to thermal protein denaturation and exhibited a higher activation energy (E-a) of 63.80 kcal/mol compared to 42.92 kcal/mol of K. fragilis. Reaction rate constants (K-d) demonstrated that the shelf-life of yeast proteins at temperatures above 60 degreesC, in whole cells was very limited.