Open AccessNUCLEAR MAGNETIC RESONANCE STUDIES OF HEMOGLOBINS, III. EVIDENCE FOR THE NONEQUIVALENCE OF α- AND β-CHAINS IN AZIDE DERIVATIVES OF METHEMOGLOBINS
Author(s) -
Donald G. Davis,
Samuel Charache,
Chien Ho
Publication year - 1969
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.63.4.1403
Subject(s) - azide , methemoglobin , heme , chemistry , histidine , hemoglobin , resonance (particle physics) , nuclear magnetic resonance , stereochemistry , biochemistry , amino acid , organic chemistry , enzyme , physics , particle physics
Nuclear magnetic resonance spectroscopy (100-MHz proton) was used to study the low-spin (S = 1/2) azide derivatives of human adult (α2 β2 ), human fetal (α2 γ2 ), Zürich (α2 β2 63 His → Arg ), and horse (α2 ′β2 ′) methemoglobins, as well as whale metmyoglobin in 0.1M deuterated phosphate at pD 7 and at 31°C. The experimental results indicate that the azide-bound heme groups of the α- and β-chains in human adult methemoglobin and of the α- and γ-chains in fetal methemoglobin are not equivalent. The affinity of the β- or γ-chain for azide ion appears larger than that of the α-chain. The nuclar magnetic resonance spectrum of hemoglobin Zürich shows that the environment of the azide-heme complex in the abnormal β-chain is altered by the substitution of arginine for histidine in the β-63 position, while the α-heme environment remains unaffected.