H-1 AND N-15 RESONANCE ASSIGNMENTS AND SECONDARY STRUCTURE OF THE CARBON-MONOXIDE COMPLEX OF SPERM WHALE MYOGLOBIN

Sequence-specific backbone H-1 and N-15 resonance assignments have bee n made for 95%, of the amino acids in sperm whale myoglobin, complexed with carbon monoxide (MbCO). Many assignments for side-chain resonanc es have also been obtained. Assignments were made by analysis of an ex tensive series of homonuclear 2D spectra, measured with unlabeled prot ein, and both 2D and 3D H-1-N-15-correlated spectra obtained from unif ormly N-15-labeled myoglobin. Patterns of medium-range NOE connectivit ies indicate the presence of eight helices in positions that are very similar to those found in the crystal structures of sperm whale myoglo bin. The resonance assignments of MbCO form the basis for determinatio n of the solution structure and for hydrogen-exchange measurements to probe the stability and folding pathways of myoglobin. They will also form a basis for assignment of the spectra of single-site mutants with altered ligand-binding properties.