Site-specific semisynthetic variant of human hemoglobin

Journal Article · Sun Jan 31 23:00:00 EST 1988 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.85.3.709· OSTI ID:6619071

Hefta, S A; Lyle, S B; Busch, M R; Harris, D E; Matthew, J B; Gurd, F R.N.

A single round of Edman degradation was employed to remove the NH/sub 2/-terminal valine from isolated ..cap alpha.. chains of human hemoglobin. Reconstitution of normal ..beta.. chains with truncated or substituted ..cap alpha.. chains was used to form truncated (des-Val/sup 1/-..cap alpha..1) and substituted (((1-/sup 13/C)Gly/sup 1/)..cap alpha..1) tetrameric hemoglobin analogs. Structural homology of the analogs with untreated native hemoglobin was established by using several spectroscopic and physical methods. Functional studies indicate that the reconstituted tetrameric protein containing des-Val/sup 1/-..cap alpha.. chains has a higher affinity for oxygen, is less influenced by chloride ions or 2,3-biphosphoglycerate, and shows lower cooperativity than native hemoglobin. These results confirm the key functional role of the ..cap alpha..-chain NH/sub 2/ terminus in mediating cooperative oxygen binding across the dimer interface. The NH/sub 2/-terminal pK/sub 1/2/ value was determined for the (/sup 13/C)glycine-substituted analog to be 7.46 +/- 0.09 at 15/sup 0/C in the carbon monoxide-liganded form. This value, measured directly by /sup 13/C NMR, agrees with the determination made by the less-direct /sup 13/CO/sub 2/ method and confirms the role of this residue as a contributor to the alkaline Bohr effect; however, it is consistent with the presence of an NH/sub 2/-terminal salt bridge to the carboxylate of Arg-141 of the ..cap alpha.. chain in the liganded form.

• Research Organization: Indiana Univ., Bloomington (USA)
• OSTI ID: 6619071
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 85:3; ISSN PNASA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTROSCOPY
AMINO ACIDS
BIOCHEMICAL REACTION KINETICS
CARBON 13
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON ISOTOPES
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL SHIFT
ELEMENTS
EVEN-ODD NUCLEI
GLOBIN
GLYCINE
HEMOGLOBIN
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
ISOTOPES
KINETICS
LIGHT NUCLEI
MAGNETIC RESONANCE
NONMETALS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PIGMENTS
PORPHYRINS
PROTEINS
REACTION KINETICS
RESONANCE
SPECTROSCOPY
STABLE ISOTOPES