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Issue 5, 2018
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Tertiary dynamics of human adult hemoglobin fixed in R and T quaternary structures

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Abstract

Protein dynamics of human adult hemoglobin and its mutants restricted in R and T quaternary states following ligand photolysis were studied by time-resolved resonance Raman spectroscopy. In the time-resolved spectra, we observed spectral changes of in-plane stretching modes of heme and the iron–histidine stretching mode of the Fe–His bond for all the hemoglobin samples. The βD99N mutant, which adopts the R state in both the ligand-bound and the deoxy forms, showed similar temporal behaviors in time-resolved resonance Raman spectra as wild-type recombinant hemoglobin until 10 μs, consistent with the fact that the mutant undergoes only the tertiary structural changes in the R state. The βN102T mutant, which adopts the T state in both the ligand-bound and the deoxy forms, showed much slower tertiary structural changes, suggesting that the EF helical motion is decelerated by the change of the intersubunit interactions. The present data indicate that the allosteric kinetic response between the interhelical hydrogen bonds of the EF helices and the intersubunit hydrogen bonds is bidirectional. The implications of these results for understanding the allosteric pathway of Hb are discussed in detail.

Graphical abstract: Tertiary dynamics of human adult hemoglobin fixed in R and T quaternary structures

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Publication details

The article was received on 14 Sep 2017, accepted on 11 Dec 2017 and first published on 11 Dec 2017


Article type: Paper
DOI: 10.1039/C7CP06287G
Citation: Phys. Chem. Chem. Phys., 2018,20, 3363-3372
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    Tertiary dynamics of human adult hemoglobin fixed in R and T quaternary structures

    S. Chang, M. Mizuno, H. Ishikawa and Y. Mizutani, Phys. Chem. Chem. Phys., 2018, 20, 3363
    DOI: 10.1039/C7CP06287G

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