Proton nuclear magnetic resonance and spectrophotometric studies of nickel(II)-iron(II) hybrid hemoglobins

Journal Article · Tue Apr 21 00:00:00 EDT 1987 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00382a019· OSTI ID:5598932

Shibayama, N; Inubushi, T; Morimoto, H; Yonetani, T

Ni(II)-Fe(II) hybrid hemoglobins, ..cap alpha..(Fe)/sub 2/..beta..(Ni)/sub 2/ and ..cap alpha..(Ni)/sub 2/..beta..(Fe)/sub 2/, have been characterized by proton nuclear magnetic resonance with Ni(II) protoporphyrin IX (Ni-PP) incorporated in apoprotein, which serves as a permanent deoxyheme. ..cap alpha..(Fe)/sub 2/..beta..(Ni)/sub 2/, ..cap alpha..(Ni)/sub 2/..beta..(Fe)/sub 2/, and NiHb commonly show exchangeable proton resonances at 11 and 14 ppm, due to hydrogen-bonded protons in a deoxy-like structure. Upon binding of carbon monoxide (CO) to ..cap alpha..(Fe)/sub 2/..beta..(Ni)/sub 2/, these resonances disappear at pH 6.5 to pH 8.5. On the other hand, the complementary hybrid ..cap alpha..(Ni)/sub 2/..beta..(Fe-CO)/sub 2/ showed the 11 and 14 ppm resonances at low pH. Upon raising pH, the intensities of both resonances are reduced, although these changes are not synchronized. Electronic absorption spectra and hyperfine-shifted proton resonances indicate that the ligation of CO in the ..beta..(Fe) subunits induced changes in the coordination and spin states of Ni-PP in the ..cap alpha.. subunits. In a deoxy-like structure, the coordination of Ni-PP in the ..cap alpha.. subunits is predominantly in a low-spin (S = 0) four-coordination state, whereas in an oxy-like structure the contribution of a high-spin (S = 1) five-coordination state markedly increased. Ni-PP in the ..beta.. subunits always takes a high-spin five-coordination state regardless of solution conditions and the state of ligation in the partner ..cap alpha..(Fe) subunits. In the ..beta..(Ni) subunits, a significant downfield shift of the proximal histidyl N/sub delta/H resonance and a change in the absorption spectrum of Ni-PP were detected, upon changing the quaternary structure of the hybrid. The chemical shifts were analyzed in terms of the E11-Val methyls vs. the porphyrin rings in hybrid Hbs.

• Research Organization: Univ. of Pennsylvania, Philadelphia
• OSTI ID: 5598932
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:8; ISSN BICHA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
ABSORPTION SPECTRA
BARYONS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL SHIFT
ELEMENTARY PARTICLES
FERMIONS
GLOBIN
HADRONS
HEAVY WATER
HEMOGLOBIN
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYPERFINE STRUCTURE
IRON COMPOUNDS
MAGNETIC RESONANCE
NICKEL COMPOUNDS
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PH VALUE
PIGMENTS
PORPHYRINS
PROTEINS
PROTONS
RESONANCE
SPECTRA
TRANSITION ELEMENT COMPOUNDS
WATER