A 1H NMR comparative study of the structure of the critical packing interfaces between helix and non-helical region in various ligation states of sperm whale myoglobin.
NMR signals arising from HisB5 N(delta)H and HisEF5 N(epsilon)H protons in sperm whale met-aquo, met-azido, met-imidazole and deoxy myoglobins have been assigned. HisB5 N(delta)H proton and N(epsilon) atom are hydrogen-bonded to peptide carbonyl oxygen of AspB1 and HisGH1 N(epsilon)H proton, respectively. This unique triad hydrogen bond stabilizes the interface between the B helix and the GH comer, which is critical to the stability of its protein folding. HisEF5 N(epsilon)H proton is hydrogen-bonded to one of the side-chain carboxyl oxygen atoms of AspH18 and this internal hydrogen bond stabilizes the orientation of the EF corner, the hinge region between the heme binding E and F helices, relative to the H helix. The assigned His NH proton signals were used as probes to investigate possible structural differences of these critical interfaces among various ligation states of myoglobin. Shift differences of the signals among the proteins strongly suggested that the AspB1-HisB5-HisGH1 and HisEF5-AspH18 hydrogen bonds are affected by heme ligation. The present study demonstrates the presence of a structural correlation between the active site and the critical interfaces in myoglobin.
Yamamoto
Y
Y
Department of Chemistry, University of Tsukuba, Japan. yash@sakura.cc.tsukuba.ac.jp
D000818:Animals; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009211:Myoglobin / Q000737:chemistry* / Q000378:metabolism; D017510:Protein Folding; D013094:Spermatozoa / Q000378:metabolism*
D009211:Myoglobin