We used Isothermal Titration Calorimetry (ITC) as a new method for the determination of enzyme activity directly in opaque, complex dairy solutions. Traditional methods for enzyme activity determination require transparent solutions. As a result, it is typical to obtain activity data in simple buffers, regardless of whether the enzymes will be used in more complex media such as milk. We have demonstrated that enzyme activity can be directly obtained in milk and other dairy fluids using ITC. Our technique reveals additional information not obtained by spectroscopy—such as the occurrence of multiple reactions at once—and directly measures the heat of the reaction rather than just showing the product concentration. Additionally, we can show differences in behavior of enzyme homologues and how their individual behaviors change based on the sample conditions, including pH and temperature.
- Genetically transform S. cerevisiae with genes for the secretion of beta-galactosidase
- Use calorimetric data to measure beta-galactosidase activity for enzyme homologs in dairy fluids