A H-1-N-15 NMR-STUDY OF HUMAN C-HA-RAS PROTEIN - BIOSYNTHETIC INCORPORATION OF N-15-LABELED AMINO-ACIDS

A H-1-N-15 NMR study was performed on the GDP-bound form of a truncated human c-Ha-ras oncogene product (171 amino acid residues). Resonance cross peaks of the backbone amide H-1-N-15 nuclei of a uniformly N-15-labeled protein were observed with heteronuclear single-quantum coherence spectroscopy (HSQC). In order to resolve overlapping cross peaks, selective N-15-labeling of one or two types of amino acid residues (Ala, Arg, Asx, Glx, Gly, His, Ile, Leu, Lys, Met, Phe, Ser, Thr, Tyr and/or Val) was carried out using appropriate E. coli mutant strains. By this procedure, all the backbone H-1-N-15 cross peaks were classified into amino acid types.