Amino–acid-type selective isotope labeling of proteins expressed in Baculovirus-infected insect cells useful for NMR studies

Culture conditions for successful amino–acid-type selective isotope labeling of proteins expressed in Baculovirus-infected insect cells are described. The method was applied to the selective labeling of the catalytic domain of c-Abl kinase with 15N-phenylalanine, 15N-glycine, 15N-tyrosine or 15N-valine. For the essential amino acids phenylalanine, tyrosine and valine high 15N-label incorporation rates of ≥90% and approximately the expected number of resonances in the HSQC spectra were observed, which was not the case for the non-essential amino acid glycine. The method should be applicable to amino-acid-type selective isotope labeling of other recombinant proteins which have not been amenable to NMR analysis.