H-NMR studies of native and fragmented subtilisin Carlsberg

NMR studies have been carried out on subtilisin Carlsberg in order to identify the sharp resonances observed in the proton spectra of the enzyme dissolved in aqueous solution. NMR spectra, obtained with the combination of spin-echo and selective excitation sequences, from both the native and inactivated protein, enabled us to assign sharp signals to subtilisin fragments derived from enzymatic autolysis (monitored by high-performance size-exclusion chromatography), rather than to mobile segments of the intact protein.