ZoBio is excited to introduce a new exclusive capability for making complex protein samples for drug discovery: isotopic labeling during mammalian expression. This ability provides the missing link between challenging-to-express proteins which require a mammalian expression system and NMR-based structural studies, which depend on isotopically labeled proteins. This new labeling option complements ZoBio’s established expertise in producing isotopically labeled samples via E. coli, expanding the toolkit available for structural and functional studies.
Our proprietary cell growth medium allows for specific amino acid labeling tailored to fit individual research needs. The resulting samples are well suited for protein-observed screening campaigns using solution-based NMR studies.
For example, we recently expressed a kinase labeled with 13C methionine. The resulting methyl NMR spectrum (Figure 1) displayed efficient isotopic label incorporation, as evidenced by observing all of the anticipated number of peaks in the NMR spectrum. Furthermore, we observed the expected changes in position of the NMR peaks when comparing the spectrum of apo kinase to that of a kinase-ligand complex, confirming the effectiveness of the labeling scheme to detect ligand binding and/or structural changes.
This innovative approach to producing isotopically labeled proteins within mammalian systems empowers researchers with new options for drug discovery, especially for complex proteins that traditional methods struggle to address. Whether NMR studies are the primary strategy or other techniques haven’t yielded sufficient insights, this capability unlocks powerful opportunities to advance research on difficult-to-express proteins.

Figure 1. The methyl NMR spectrum displayed efficient isotopic label incorporation.