A Simplified Method for Measuring Secreted Invertase Activity in Saccharomyces cerevisiae

The measurement of sucrose hydrolysis to glucose and fructose in yeast is valuable for many aspects of yeast cell biology and metabolic analysis, and has been used extensively to understand the genetics of the SNF1 kinase. However, a simple and rapid method describing how to perform this assay for new users is lacking. Here, we review various methods used to measure invertase activity. We focus on a method based on a colorimetric assay that was first described by Goldstein and Lampen in 1975. Our report not only describes a simple and rapid application of this method to measure secreted invertase enzymatic activity from yeast whole cells for new users, but also establishes optimized times for assay conditions. The method utilizes a small volume of yeast culture in which the entire procedure can be performed in less than an hour. Very few reports offer a step-by-step method that can be readily used without prior knowledge of the procedure, providing the impetus for this report. The optimizations described in this report allow increased sensitivity when comparing subtle changes.