Dataset Information

Autoxidation and oxygen binding properties of recombinant hemoglobins with substitutions at the ?Val-62 or ?Val-67 position of the distal heme pocket.

ABSTRACT: The E11 valine in the distal heme pocket of either the ?- or ?-subunit of human adult hemoglobin (Hb A) was replaced by leucine, isoleucine, or phenylalanine. Recombinant proteins were expressed in Escherichia coli and purified for structural and functional studies. (1)H NMR spectra were obtained for the CO and deoxy forms of Hb A and the mutants. The mutations did not disturb the ?1?2 interface in either form, whereas the H-bond between ?His-103 and ?Gln-131 in the ?1?1 interfaces of the deoxy ?-subunit mutants was weakened. Localized structural changes in the mutated heme pocket were detected for the CO form of recombinant Hb (rHb) (?V62F), rHb (?V67I), and rHb (?V67F) compared with Hb A. In the deoxy form the proximal histidyl residue in the ?-subunit of rHb (?V67F) has been altered. Furthermore, the interactions between the porphyrin ring and heme pocket residues have been perturbed in rHb (?V62I), rHb (?V62F), and rHb (?V67F). Functionally, the oxygen binding affinity (P50), cooperativity (n50), and the alkaline Bohr Effect of the three ?-subunit mutants and rHb (?V67L) are similar to those of Hb A. rHb (?V67I) and rHb (?V67F) exhibit low and high oxygen affinity, respectively. rHb (?V67F) has P50 values lower that those reported for rHb (?L29F), a B10 mutant studied previously in our laboratory (Wiltrout, M. E., Giovannelli, J. L., Simplaceanu, V., Lukin, J. A., Ho, N. T., and Ho, C. (2005) Biochemistry 44, 7207-7217). These E11 mutations do not slow down the autoxidation and azide-induced oxidation rates of the recombinant proteins. Results from this study provide new insights into the roles of E11 mutants in the structure-function relationship in hemoglobin.

SUBMITTER: Tam MF

PROVIDER: S-EPMC3757212 | biostudies-literature | 2013 Aug

REPOSITORIES: biostudies-literature

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Autoxidation and oxygen binding properties of recombinant hemoglobins with substitutions at the αVal-62 or βVal-67 position of the distal heme pocket.

Tam Ming F MF Rice Natalie W NW Maillett David H DH Simplaceanu Virgil V Ho Nancy T NT Tam Tsuey Chyi S TCS Shen Tong-Jian TJ Ho Chien C

The Journal of biological chemistry 20130718 35

The E11 valine in the distal heme pocket of either the α- or β-subunit of human adult hemoglobin (Hb A) was replaced by leucine, isoleucine, or phenylalanine. Recombinant proteins were expressed in Escherichia coli and purified for structural and functional studies. (1)H NMR spectra were obtained for the CO and deoxy forms of Hb A and the mutants. The mutations did not disturb the α1β2 interface in either form, whereas the H-bond between αHis-103 and βGln-131 in the α1β1 interfaces of the deoxy ...[more]

PMID: 23867463

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Dataset Information

Autoxidation and oxygen binding properties of recombinant hemoglobins with substitutions at the ?Val-62 or ?Val-67 position of the distal heme pocket.

Publications

Autoxidation and oxygen binding properties of recombinant hemoglobins with substitutions at the αVal-62 or βVal-67 position of the distal heme pocket.

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