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    • Keywords


      Hybrid hemoglobin; -SH reactivity study; EPR; subunit heterogeneity

    • Abstract


      The sulphhydryl environment in various mixed-metal hybrid hemoglobins, viz. α2(Cu)-β2(FeCO), α2(FeCO)-β2(Cu), α2(Cu)-β2(Ni), α2(Ni)-β2(Cu), was studied by reacting them with the sulphhydryl reagent, 4,4′-dithiodipyridine (4-PDS). The reactivity was compared with that of HbCO, NiHb and CuHb. It is found that there exists a correlation between conformational change and metal ion environment, not only at the extreme R and T states but also the intermediate conformations. EPR examinations of these hybrids show that both in R state-[Cu(II)-Fe(II)] and T state-[Cu(II)-Ni(II)] hybrids at neutral pH and in the absence of IHP, CuPPIX, irrespective of the subunit in which it is present, has a mixed-metal ion environment: Species 1, a five-coordinated Cu2+ complex with strong proximal histidine bond and species 2, a four-coordinated complex without any covalent linkage with Nε F8-histidine.

    • Author Affiliations


      S Ramasamy1 Swarnalatha Venkateshrao1 J M Rifkind2 P T Manoharan1

      1. Department of Chemistry and Regional Sophisticated Instrumentation Centre, Indian Institute of Technology, Madras, Chennai - 600 036, India
      2. Molecular Dynamics Section, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD - 21224, USA
    • Dates

  • Journal of Chemical Sciences | News

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