ZoBio is excited to expand its exclusive capability for making complex protein samples for drug discovery with ¹³C-methyl MILV isotopic labeling during HEK293 mammalian expression. Our labelling method allows for specific amino acid labeling tailored to fit your individual research needs. The resulting samples are well suited for our protein-observed screening campaigns using solution NMR studies. This innovative approach to producing isotopically labeled proteins in a mammalian system empowers researchers with new options for drug discovery. Irrespective of 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.

Previously we expressed a kinase labeled with 13C methionine (Isotopic Labeling in Mammalian Expression: The Missing Link for NMR Studies of Hard-to-Express Proteins - ZoBio - Drug Discovery Technology). This time, we simultaneously incorporated ¹³C-labelled methionine, isoleucine, leucine and valine in a secreted cytokine. The methyl region of the 13C-HSQC spectrum (Figure 1) displayed the expected number of peaks, underscoring the efficient incorporation of isotopic label. Furthermore, we observed changes in position of the NMR peaks when comparing the spectrum of apo cytokine to that of a cytokine-ligand complex, confirming the effectiveness of the labeling scheme to detect ligand binding and/or structural changes.

Figure 1. The methyl NMR spectrum displayed efficient isotopic label incorporation and chemical shifts indicative of ligand binding.