Protein Expression and Purification Series - Bio-Rad

Protein Expression and Purification Series
Dear Educator
One of the great promises of the biotechnology industry is the ability to produce biopharmaceuticals to
treat human disease. Genentech pioneered the development of recombinant DNA technology to produce
products with a practical application. In the mid-1970s, insulin, used to treat diabetics, was extracted from
the pancreas glands of swine and cattle that were slaughtered for food. It would take approximately 8,000
pounds of animal pancreas glands to produce one pound of insulin. Rather than extract the protein from
animal sources, Genentech engineered bacterial cells to produce human insulin, resulting in the world’s first
commercial genetically engineered product.
Producing novel proteins in bacteria or other cell types is not simple. Active proteins are often comprised
of multiple chains of amino acids with complex folding and strand interactions. Commandeering a
particular cell to reproduce the native form presents many challenges. Considerations of cell type, plasmid
construction, and purification strategy are all part of the process of developing a recombinant protein.
In the Protein Expression and Purification Series students will explore the process of developing a
recombinant protein by inducing E. coli to express the protein of interest, dihydrofolate reductase, which
is a target for certain cancer treatments. Students will learn how to recover the protein from other cellular
components and then purify it away from other proteins in the cell. The dominant method of purifying
proteins is chromatography, and this series utilizes one of the most powerful types used today: affinity
chromatography. In addition, two options for purification are provided—one on a small scale, using
centrifugation, and the other a larger scale, with purification instrumentation. The latter provides a workflow
and equipment experience that parallels biomanufacturing processes used today.
Many biology educators have used the pGLO system in which a cloned green fluorescent protein (GFP)
serves as a model system for transformation and chromatographic separation. The visibility of the protein
is a great teaching model and introduction to chromatography. However, in the laboratory and in industrial
settings, very few proteins are visible. The Protein Expression and Purification Series is a real-world model
system that provides hands-on experience for students to learn the key process in biotechnology—taking
recombinant DNA through production to purified protein.
The Biotechnology Explorer program has a long history of partnering with educators to create laboratory
experiences that prepare students for today’s careers and providing the understanding that is required
for citizens in the rapidly advancing technologies that impact our daily lives. The Protein Expression and
Purification Series was developed in response to educators’ desire to provide students with authentic
laboratory experiences relevant to research and industrial applications. We wish to acknowledge the
contribution of several collaborators in the development of the curriculum and assessment utilized in the
series: Jim DeKloe from Solano Community College, Kirk Land from University of the Pacific, Joann Lau
from Bellarmine University, and Cindy Gay from Steamboat Springs High School. We thank each of these
educators for their invaluable guidance and contributions to this series.
We continually strive to improve our curricula and products. We welcome your suggestions and ideas!
Biotechnology Explorer Team
Bio-Rad Laboratories
6000 James Watson Dr.
Hercules, CA 94547
biotechnology_explorer@bio-rad.com
explorer.bio-rad.com
3