Carbon-13-enriched S-methylmethionyl residues as a probe of protein conformation

Interlobe Communication in 13C-Methionine-Labeled Human Transferrin

“…Most previous work on 13 C-labeled proteins has been confined to those of molecular mass <30 kDa (Kuboniwa et al, 1995;Slupsky & Sykes, 1995;Wagner, 1993), although some early work on [ 13 C]His-labeled alkaline phosphatase (a dimer of 2 × 47 kDa) demonstrated the advantages of 13 C labeling for the study of larger proteins (Otvos & Browne, 1980). Chemical 13 C labeling of Met residues of small proteins at -CH 3 has been widely used [e.g., Jones et al (1976), Deber et al (1978), and Harina et al (1978)], but such labeling is possible only for chemically accessible Met residues, unless the protein is unfolded before treatment, and a lower percentage of enrichment is obtained than is possible by recombinant technology. In the present work, we have labeled all nine Met residues of human transferrin (Figure 1) with [ -13 C]Met using recombinant DNA methods.…”

Direct observation by carbon-13 nuclear magnetic resonance of membrane-bound human myelin basic protein

“…Selective l3C enrichment by this procedure has been used in our laboratory to prepare bovine and human MBP S-methylated and "reduced" at its two Met residues (numbers 21 and 167) (Deber et al, 1978). Other proteins including horse cytochrome c (Schejter et al, 1978) and bovine pancreatic trypsin inhibitor (BPTI) (Harina et al, 1978) have been similarly studied.…”

Denaturation studies by carbon-13 nuclear magnetic resonance on modified basic pancreatic trypsin inhibitor using the novel S-[13C]methyl methionyl probe

“…We reported in a preliminary communication that the diastereomers of SM-BPTI can be distinguished spectroscopically by 13C NMR and that the chemical-shift separation of the l3C methyl signals provides a useful and sensitive probe for monitoring conformational changes in the protein. 7 The spectroscopic resolution of the resonances from the diastereomers in an 5-methyl methionyl containing protein had not been pre-0002-7863/80/1502-1120$01.00/0 viously observed. We now report the results of further investigations which have identified factors contributing to the nonequivalence of the methyl signals in SM-BPTI.…”