Carbon‐13 NMR study of the B9(Asp) mutant of human insulin: Sequence‐specific carbon‐13 assignments and structural information

The resonances of the proton‐bearing 13 C nuclei at natural abundance were assigned for the solution dimer of the B9(Asp) mutant of human insulin. The assignments are based on a combination of direct and relayed 1 H 13 C correlated spectra, i.e. SQC, SQC‐HOHAHA and HMQC‐COSY, and the previously assigned 1 H spectrum. The study proves valuable not only because of the 13 C assignments, but also because it provides a verification, a completion and a few corrections of the previous 1 H assignments. Finally, the obtained 13 C assignments support the previously reported correlation between the secondary 13 C α and 13 C β chemical shifts and the secondary structure of proteins.