Working with Enzymes - Where Is Lactose Digested? An Enzyme Assay for Nutritional Biochemistry Laboratories

Abstract

At Georgia Southern University, we offer a sophomore-level introductory biochemistry course that is aimed at nutrition and chemistry education majors. The laboratory portion of this course has long lacked an experimental introduction to enzymes. We have developed a simple enzyme assay utilizing lactase enzyme from crushed LactAid tablets and a 5% lactose solution ("synthetic milk"). In the experiment, the students assay the activity of the enzyme on the "synthetic milk" at pHs of approximately 1, 6, and 8 with the stated goal of determining where lactose functions in the digestive tract. The activity of the lactase may be followed chromatographically or spectrophotometrically. The experiment, which is actually a simple pH assay, is easily implemented in allied health chemistry laboratory courses and readily lends itself to adaptation for more complex kinetic assays in upper-level biochemistry laboratory courses. The experimental details, including a list of required supplies and hints for implementation, are provided.

Measurement of Enzyme Kinetics by Use of a Blood Glucometer: Hydrolysis of Sucrose and Lactose

“…In this Journal , several articles have described the enzymatic hydrolysis of lactose by enzyme lactase. − Lactose is hydrolyzed into α-glucose and β-galactose; α-glucose and β-galactose equilibrate with β-glucose and α-galactose, the so-called mutarotation. The enzyme lactase (β-galactosidase, EC 3.2.1.26) cleaves the glycosidic linkage of β-galactose in the lactose molecule.…”

A Laboratory Exercise for Photochemistry and Photobiology: Production of Hydrogen Peroxide

“…Its synthesis can be detected after 20 min of illumination and monitored using a simple enzymatic analysis with horseradish peroxidase. Related analyses using horseradish peroxidase have been published in this Journal (4,5).…”

Bioanalytical Experiments for the Undergraduate Laboratory: Monitoring Glucose in Sports Drinks

“…Most of those described either have been immunoassay experiments (1,2) or have outlined the use of enzyme electrodes (3)(4)(5)(6)(7)(8). Surprisingly, despite some soluble enzyme assay experiments with a biochemical focus (see Pope et al [9] and references therein), we are unaware of any undergraduate experiments employing solution enzyme assays for analytical purposes.…”