Open AccessHemoglobin redux: combining neutron and X‐ray diffraction with mass spectrometry to analyse the quaternary state of oxidized hemoglobins
Author(s) -
Mueser Timothy C.,
Griffith Wendell P.,
Kovalevsky Andrey Y.,
Guo Jingshu,
Seaver Sean,
Langan Paul,
Hanson B. Leif
Publication year - 2010
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s090744491002545x
Subject(s) - protein quaternary structure , hemoglobin , protonation , chemistry , crystallography , neutron diffraction , bohr effect , crystal structure , protein subunit , biochemistry , gene , organic chemistry , ion , oxygen–haemoglobin dissociation curve
Improvements in neutron diffraction instrumentation are affording the opportunity to re‐examine the structures of vertebrate hemoglobins and to interrogate proton and solvent position changes between the different quaternary states of the protein. For hemoglobins of unknown primary sequence, structural studies of cyanomethemoglobin (CNmetHb) are being used to help to resolve sequence ambiguity in the mass spectra. These studies have also provided additional structural evidence for the involvement of oxidized hemoglobin in the process of erythrocyte senescence. X‐ray crystal studies of Tibetan snow leopard CNmetHb have shown that this protein crystallizes in the B state, a structure with a more open dyad, which possibly has relevance to RBC band 3 protein binding and erythrocyte senescence. R‐state equine CNmetHb crystal studies elaborate the solvent differences in the switch and hinge region compared with a human deoxyhemoglobin T‐state neutron structure. Lastly, comparison of histidine protonation between the T and R state should enumerate the Bohr‐effect protons.