TY - JOUR
T1 - Proton NMR studies of myohemerythrin from Themiste zostericola
AU - Wang, Zhigang
AU - Martins, Laura
AU - Ellis, Walther R.
AU - Que, Lawrence
N1 - Funding Information:
Acknowledgements This work was supported by grants from the National Science Foundation (MCB-9405723, L. Q.) and the National Institutes of Health (GM43507, W. R. E.).
PY - 1997/2
Y1 - 1997/2
N2 - One- and two-dimensional NMR experiments have been carried out on different forms of myohemerythrin (MHr), a monomeric 13.9-kDa oxygen carrier, focusing on paramagnetically shifted proton resonances. Compared to the corresponding forms of octameric hemerythrin (Hr), all of the MHr forms exhibit spectra with better resolution and signal-to-noise ratios. The metMHr spectra allow the differentiation of the signals from the N(δ)-H protons of the five N(r)-coordinated His ligands and those from the bridging Asp and Glu ligands. The ID spectra of deoxyMHr exhibit a number of relatively sharp features including three solvent-exchangeable peaks that account for five protons. One of these His N-H protons exchanges more slowly with solvent than the other four and is assigned to His 54, which, by analogy to the crystal structure of deoxy-Hr, is the only His ligand that is hydrogen-bonded to an amine acid residue, Glu24 in this case. One-dimensional NOE results on the non-exchangeable signals clearly show the connectivities among the α and β protons of the bridging Asp111, and the α,β, and γ protons of the bridging Glu58 ligands. One-dimensional NOE experiments performed on the N-H proton signals of the coordinated His ligands, together with the COSY results, help to identify the geminal β protons of the His ligands. Upon the binding of N3/- to one of the Fe(II) sites in deoxyMHr, the overlapping His N(δ)-H protonsignals observed in the deoxyMHr spectrum are resolved into individual signals; these have been correlated to the corresponding signals in deoxyMHr by saturation transfer experiments. Similarly, all five His N-H protons are resolved in the 1H NMR spectrum of the deoxy form of the single point mutant L103N MHr. However, all five N-H protons readily exchange with solvent, indicating that the mutation affects the hydrogen-bonding interaction between His54 and Glu24.
AB - One- and two-dimensional NMR experiments have been carried out on different forms of myohemerythrin (MHr), a monomeric 13.9-kDa oxygen carrier, focusing on paramagnetically shifted proton resonances. Compared to the corresponding forms of octameric hemerythrin (Hr), all of the MHr forms exhibit spectra with better resolution and signal-to-noise ratios. The metMHr spectra allow the differentiation of the signals from the N(δ)-H protons of the five N(r)-coordinated His ligands and those from the bridging Asp and Glu ligands. The ID spectra of deoxyMHr exhibit a number of relatively sharp features including three solvent-exchangeable peaks that account for five protons. One of these His N-H protons exchanges more slowly with solvent than the other four and is assigned to His 54, which, by analogy to the crystal structure of deoxy-Hr, is the only His ligand that is hydrogen-bonded to an amine acid residue, Glu24 in this case. One-dimensional NOE results on the non-exchangeable signals clearly show the connectivities among the α and β protons of the bridging Asp111, and the α,β, and γ protons of the bridging Glu58 ligands. One-dimensional NOE experiments performed on the N-H proton signals of the coordinated His ligands, together with the COSY results, help to identify the geminal β protons of the His ligands. Upon the binding of N3/- to one of the Fe(II) sites in deoxyMHr, the overlapping His N(δ)-H protonsignals observed in the deoxyMHr spectrum are resolved into individual signals; these have been correlated to the corresponding signals in deoxyMHr by saturation transfer experiments. Similarly, all five His N-H protons are resolved in the 1H NMR spectrum of the deoxy form of the single point mutant L103N MHr. However, all five N-H protons readily exchange with solvent, indicating that the mutation affects the hydrogen-bonding interaction between His54 and Glu24.
KW - Myohemerythrin
KW - Nuclear magnetic resonance
KW - Solvent-exchangeable protons
KW - Themiste zostericola
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U2 - 10.1007/s007750050106
DO - 10.1007/s007750050106
M3 - Article
AN - SCOPUS:0030889340
SN - 0949-8257
VL - 2
SP - 56
EP - 64
JO - Journal of Biological Inorganic Chemistry
JF - Journal of Biological Inorganic Chemistry
IS - 1
ER -