Design of a Robust Undergraduate Biochemistry Laboratory Module Based on a Purification Scheme for Bovine Serum Albumin

Abstract

This paper describes an undergraduate biochemistry laboratory module consisting of a set of experiments designed around a purification scheme for bovine serum albumin (BSA). Students purify BSA from cow plasma by a combination of salt and acetone precipitation, equilibrium dialysis, ion exchange, and size exclusion chromatography. Students use the bromocresol green–BSA complex assay to quantify albumin at each step in the scheme and generate a purification table. In addition, trace amounts of IgG’s and nucleases, the major contaminants in BSA purification, are probed by Western blotting and DNase assay, respectively. This module exposes students to the principles and techniques of separation of proteins based on solubility, size, and surface charge. In addition, students learn the concept of limit of detection of analytical techniques such as SDS-PAGE and Western blotting. The module utilizes two 3-h laboratory periods, with a 1-h prelab lecture per week, for about 6 weeks. Depending on class size, groups consist of two to four students. The module is suitable for students who have completed a semester of biochemistry. Instructors can extend the module to advanced level laboratory by including enzyme kinetics and protein structure–function studies based on albumin’s pseudoesterase activity and intrinsic tryptophan fluorescence, respectively.