Using a Simple, Inexpensive Undergraduate Isoelectric Focusing Experiment for Proteins and Nanomolecules To Help Students Understand Isoelectric Point and Its Real-World Applications

Abstract

A laboratory experiment was designed for upper-level undergraduate students in a bioanalytical course to demonstrate the concept of isoelectric point (pI) and the theoretical and practical applications of isoelectric focusing (IEF). This simple and inexpensive IEF procedure requires the same minigel SDS-PAGE equipment that is already available in most biochemistry and biology laboratories. Students first use published mathematical formulas to predict the pI of a nanomolecule known as a polyamidoamine dendrimer and subsequently determine its pI by preparing and running an IEF gel using common proteins with well-established pI values as standards. The pI of the nanomolecule is determined from a calibration plot generated between migration distances and pIs of the protein standards. This experiment has been successfully performed by over 50 bioanalytical students over the past five years. Evidence from in-lab problems, lab reports, and postlab quizzes shows that the use of medical examples, protein computer ...