Heme Transfer Reactions: An Important Prerequisite for Synthetic Oxygen Carriers

Authors: Jan PAUL, Wenhua CHEN, Per-Ingvar OHLSSON, Michael SMITH

Abstract: Electronic changes of iron- and metal free porphyrins are reviewed in light of their importance to modify the ferri/ferro reduction potential and energy dissipation between ligated carbon monoxide and the porphyrin chelate. Substitutions at positions 2 and 4 are effective ways to exercise this influence. Other measures include exposure to water and modifications of axial ligation, including the \lq three-ligand' case. These measures will also influence the stability of recombined hemin-protein entities, as apparent from the kinetics of heme-transfer from a modified donor protein to apomyoglobin, but the stability appears to be related to the bulkiness of 2,4-substitutional groups rather than to electron availability. It is suggested that the altered stability is a secondary effect from enhanced exposure to water in the crevice.


Full Text: PDF