Amide proton hydrogen exchange rates for sperm whale myoglobin obtained from N-15-H-1 NMR spectra

The hydrogen exchange behavior of exchangeable protons in proteins can prov ide important information for understanding the principles of protein struc ture and function. The positions and exchange rates of the slowly-exchangin g amide protons in sperm whale myoglobin have been mapped using N-15-H-1 NM R spectroscopy. The slowest-exchanging amide protons are those that are hyd rogen bonded in the longest helices, including members of the B. E, and H h elices. Significant protection factors were observed also in the A, C, and G helices, and for a few residues in the D and F helices. Knowledge of the identity of slowly-exchanging amide protons forms the basis for the extensi ve quench-now kinetic folding experiments that have been performed for myog lobin, and gives insights into the tertiary interactions and dynamics in th e protein.