A simple micropreparative gel electrophoresis technique for purification of proteins, nucleic acids, and bioconjugates

Abstract

The biochemical and biomedical fields hinge on the ability to effectively separate and purify biological macromolecules. Though this need is largely addressed with a variety of chromatographic and electrophoretic purification techniques, such techniques are usually laborious, time-consuming, and often require complex and costly instalments that are inaccessible to most laboratories. In this work, we introduce a simple micro-preparative (MP) method based on polyacrylamide gel electrophoresis (PAGE) to purify biological samples containing proteins, nucleic acids, and complex bioconjugates. Using a conventional vertical slab system, we demonstrate the extraction of purified DNA, proteins, and DNA-protein bioconjugates from their respective mixtures using MP-PAGE. We apply this system to recover DNA from a ladder mixture with yields of up to 90%, compared to the 58% yield obtained using specialized commercial devices. We also demonstrate the purification of folded enhanced yellow fluorescence protein (EYFP) from crude cell extract with 90% purity, comparable to purities achieved using a two-step size exclusion and immobilized metal-ion affinity chromatography purification procedure. Finally, we demonstrate the successful isolation of an EYFP-DNA bioconjugate sample that otherwise could not be processed using the two-step chromatography procedure. MP-PAGE thus offers a rapid and versatile means of purifying a variety of biomolecules without the need for specialized equipment.