Cell Growth Media and Protein Production

Bacterial Media

The over-expression of protein using E. coli is the most popular way to obtain labeled protein for use in NMR studies. This is achieved by growing E. coli cells and inducing protein expression in a suitably isotope-enriched cell culture medium. A minimal medium is a cell culture medium that only includes glucose or glycerol or pyruvate as the sole source of carbon and either ammonium chloride or ammonium sulfate as the sole source of nitrogen for the expressed protein. A rich medium contains amino acids as well as some level of glucose for protein production.

CIL offers a number of products for the expression of labeled protein for use in NMR studies. These include reagents for use in minimal media as well as rich bacterial cell media that is ready to use as-is or after dilution with water. CIL also offers Celtone Powder, a labeled additive for use with minimal media as well as Spectra 9 media, a minimal medium that contains 1 gram per liter of Celtone Powder. CIL also sells E. coli OD media that is produced by Silantes Gmbh, a company located in Munich, Germany.

Insect Cell Media

The use of the baculovirus expression system (BEVS) for insect cells cultured in isotope-labeled media has shown to be a proven technique for the production of isotope-labeled membrane proteins, most notably, G-protein coupled receptors (GPCR)s. CIL is proud to have pioneered a chemically defined culture medium that has been used with Spodoptera frugiperda (SF9) cells. This medium, BioExpress 2000^®, can be manufactured with uniform labeling or amino acid specific labeling. Unlabeled trial sizes are available for use in checking feasibility and optimization prior to using labeled media.

Mammalian Cell Media

As target proteins increase in size and complexity, the probability of obtaining properly folded protein expressed in E. coli decreases. One must then turn to expressing protein using eukaryotic cells of which mammalian cell lines are often preferred. CIL is proud to offer BioExpress^® 6000, a cell culture medium that is suitable for culturing a limited number of mammalian cell lines. BioExpress 6000 is a chemically defined medium whose formulation is modeled after DMEM and thus it is highly suitable for culturing HEK293 cells. To determine if BioExpress 6000 supports growth of a particular cell line, it is recommended that the cells are first cultured in DMEM. If DMEM supports the growth of the cells, then BioExpress 6000 should also work. If the cells require fetal bovine serum (FBS) or fetal calf serum (FCS) to be present, then dialyzed FBS or FCS in conjunction with BioExpress 6000 should be used. BioExpress 6000 comes as a powder with directions on reconstitution. Normally the medium contains CaCl, however, CIL provides a version that does not contain CaCl₂ for use with nonadherent growths. Since BioExpress 6000 is chemically defined, the user can specify which amino acids that are to be desired to be labeled (CGM-6500-CUSTOM). CIL also offers unlabeled BioExpress 6000 to assess growth prior to purchasing and using a labeled version.

Yeast Media and Reagents

Yeast represents the most popular eukaryotic cell type used for protein expression. Yeast cells are easily grown, genetically manipulated, and can produce high yields of expressed protein. The three genera used for producing labeled protein for NMR purposes are Pichia, Saccharomyces, and Kluyveromyces. CIL is pleased to offer a variety of labeled carbon sources for yeast expression as well as media.

Frequently Asked Question

Will BioExpress^® 6000 work for culturing my cells? There is no known medium that can successfully be used to culture all types of mammalian cells. It is therefore recommended that the user checks the growth of their cell line using DMEM prior to using BioExpress 6000.