JBC, Vol. 250, Issue 16, 6381-6402, Aug, 1975
Studies of individual carbon sites of proteins in solution by natural abundance carbon 13 nuclear magnetic resonance spectroscopy. Strategies for assignments
E. Oldfield, R. S. Norton and A. Allerhand
Natural abundance 13C Fourier transform NMR spectra (at 15.18 MHz, in 20-mm
sample tubes) of aqueous native proteins yield numerous narrow single
carbon resonances of nonprotonated aromatic carbons. Techniques for the
assignment of these resonances are presented. Each technique is applied to
one or more of the following proteins: ferricytochrome c from horse heart
and Candida krusei, ferrocytochrome c and cyanoferricytochrome c from horse
heart, lysozyme from hen egg white, cyanoferrimyoglobins from horse and
sperm whale skeletal muscle, and carbon monoxide myoglobin from horse. In
all of the protein spectra we have examined, methine aromatic carbons give
rise to broad bands. Studies of the narrow resonances of nonprotonated
aromatic carbons of proteins are facilitated by removal of these broad
bands by means of the convolution-difference method, preferably from
spectra recorded under conditions of noise-modulated off-resonance proton
decoupling. We present a summary of the chemical shift ranges for the
various types of nonprotonated aromatic carbons of amino acid residues and
hemes of diamagnetic proteins, based on our results for hen egg white
lysozyme, horse heart ferrocytochrome c, horse carbon monoxide myoglobin,
and carbon monoxide hemoglobins from various species...