Reverse Bohr effect on the oxygen-binding affinity of heme embedded in a bilayer of liposome as a hemoglobin model: PH-induced oxygen uptake and evolution by aqueous synthetic lipid-heme solution

Makoto Yuasa, Yuichiroh Tani, Hiroyuki Nishide, Eishun Tsuchida

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Abstract

The oxygen-binding affinity (p1/2; oxygen pressure at 50% binding for the heme) of a heme derivative embedded in a bilayer of natural phospholipid liposomes was influenced by the solution pH: the p1/2 value of the liposome-lipid-heme increased with pH {Bohr coefficient, r = d[log(p1/2)]d(pH) = +0.09 to +0.32}, which is the reverse of the Bohr effect for hemoglobin. This pH dependence was affected by the composition of the liposome-lipid-heme. Its mechanism is discussed in relation to the surrounding lipid bilayer structure and protonation equilibrium of the imidazole ligand. pH-induced oxygen-uptake and -evolution was observed, in a process which was sensitive to ±1 unit of pH change at pH 7.

Original languageEnglish
Pages (from-to)1917-1920
Number of pages4
JournalJournal of the Chemical Society, Dalton Transactions
Issue number8
DOIs
Publication statusPublished - 1987

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ASJC Scopus subject areas

  • Chemistry(all)

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