The Journal of Biochemistry
Online ISSN : 1756-2651
Print ISSN : 0021-924X
1H-NMR Comparative Study of the Active Site in Shark (Galeorhinus japonicus), Horse, and Sperm Whale Deoxy Myoglobins
Yasuhiko YamamotoKoji IwafuneRiichirô ChûjôYoshio InoueKiyohiro ImaiTomohiko Suzuki
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1992 Volume 112 Issue 3 Pages 414-420

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Abstract

1H-NMR spectra of deoxy myoglobins (Mbs) from shark (Galeorhinus japonicus), horse, and sperm whale have been studied to gain insights into their active site structure. It has been demonstrated for the first time that nuclear Overhauser effect (NOE) can be observed between heme peripheral side-chain proton resonances of these paramagnetic complexes. Val-E11 methyl and His-F8 CδH proton resonances of these Mbs were also assigned from the characteristic shift and line width. The hyperfine shift of the former resonance was used to calculate the magnetic anisotropy of the protein. The shift analysis of the latter resonance, together with the previously assigned His-F8 NδH proton resonance, revealed that the strain on the Fe-Nε bond is in the order horse Mb_??_whale Mb<shark Mb and that the hydrogen bond strength of the His-F8 NδH proton to the main-chain carbonyl oxygen in the preceding turn of the F helix is in the order shark Mb<horse Mb<whale Mb. Weaker Fe-porphyrin interaction in shark Mb was manifested in a smaller shift of the heme methyl proton resonance and appears to result from distortion of the coordination geometry in this Mb. Larger strain on the Fe-Nε bond in shark Mb should be to some extent attributed to its lowered O2 afnity (P50=1.1mmHg at 20°C), compared to whale and horse Mbs.

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© The Japanese Biochemical Society
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