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Structural properties of 2/2 hemoglobins: The group III protein from Helicobacter hepaticus
Author(s) -
Nothnagel Henry J.,
Winer Benjamin Y.,
Vuletich David A.,
Pond Matthew P.,
Lecomte Juliette T. J.
Publication year - 2011
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1002/iub.430
Subject(s) - chemistry , ferrous , heme , ferric , hemoglobin , campylobacter jejuni , proton nmr , amino acid , crystallography , stereochemistry , biochemistry , bacteria , inorganic chemistry , biology , genetics , organic chemistry , enzyme
The ε‐proteobacterium Helicobacter hepaticus (Hh) contains a gene coding for a hemoglobin (Hb). The protein belongs to the 2/2 Hb lineage and is representative of group III, a set of Hbs about which little is known. An expression and purification procedure was developed for Hh Hb. Electronic absorption and nuclear magnetic resonance (NMR) spectra were used to characterize ligation states of the ferric and ferrous protein. The p K a of the acid/alkaline transition of ferric Hh Hb was 7.3, an unusually low value. NMR analysis of the cyanomet complex showed the orientation of the heme group to be reversed when compared with most group I and group II 2/2 Hbs. Ferrous Hh Hb formed a stable cyanide complex that yielded NMR spectra similar to those of the carbonmonoxy complex. All forms of Hh Hb were self‐associated at NMR concentrations. Comparison was made to the related Campylobacter jejuni 2/2 Hb (Ctb), and the amino acid conservation pattern of group III was reinspected to help in the generalization of structure–function relationships. © 2011 IUBMB IUBMB Life, 63(3): 197–205, 2011