Quantitative Determination of Lactase

Abstract

A simple and quick assay is described for the determination of the lactase activity of crude enzyme preparations. Results are available in 2 hr. from as little as 2 rag. of material. Fifteen minutes' incubation at 37 C. is used for the enzymatic reaction on a pure lactose substrate. The lactase activity is related to the amount of glucose released by the hydrolysis, as determined by an enzymatic micro-method. The effects of substrate concentration, pit, temperature, and related factors are investigated. The assay procedure was advantageously employed in a preliminary quantitative screening of lactaseproducing organisms which could utilize whey in their growth.