Identification of a nickel(II) binding site on hemoglobin which confers susceptibility to oxidative deamination and intramolecular cross-linking.
Complexation of Ni(II) with native state recombinant hemoglobin is shown to produce NH2-terminal deamination and globin cross-linking in the presence of the oxidant potassium peroxymonosulfate (OxoneTM). Both the oxidative deamination and cross-linking are exclusive to the beta chains. Recombinant hemoglobin mutants have been created to identify protein sequence requirements for these reactions. It was found that His-2 of the beta globin is required for redox active Ni(II) complexation, oxidative deamination, and cross-linking. The oxidative deamination results in the formation of a free carbonyl in place of the NH2-terminal amine of the beta chain. Most cross-linking of the beta globin occurs intramolecularly, forming beta globin dimers. Structural characterization of the beta globin dimers indicates the presence of heterogeneous cross-links within the central hemoglobin cavity between the NH2 terminus of one beta chain and the COOH-terminal region of the other.
Levine
J
J
Somatogen Inc., Boulder, Colorado 80301, USA.
Weickert
M
M
Pagratis
M
M
Etter
J
J
Mathews
A
A
Fattor
T
T
Lippincott
J
J
Apostol
I
I
D000595:Amino Acid Sequence; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D003641:Deamination; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D006454:Hemoglobins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009532:Nickel / Q000378:metabolism*; D010084:Oxidation-Reduction; D010449:Peptide Mapping; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013464:Sulfuric Acids / Q000737:chemistry
D006454:Hemoglobins; D011994:Recombinant Proteins; D013464:Sulfuric Acids; D009532:Nickel; C048813:potassium peroxymonosulfuric acid