title: Optical and EPR spectroscopy studies on haem arginate, a new compound used for treatment of porphyria.
abstract: A protohaem compound, used for treatment of porphyrias, has been studied to elucidate its state of aggregation. EPR and absorption spectroscopy measurements reveal that 38.3 mM protohaem, dissolved in 40% 1,2-propanediol/10% ethanol/water solution, also containing 153 mM arginine, is partly EPR silent. It exists as high molecular weight aggregates and probably also as mu-oxo-dimers. Dilution in the aqueous alcohol solution dissolves the aggregates first to oligomers and dimers, and finally to monomers (Kdiss = 24 X 10(-6)M). When haem is diluted in 0.9% sodium chloride, a fully monomeric state is not reached even at 1 microM concentration. At 3.5 microM concentration, that used for infusion in patients, the haem is still totally aggregated.
authors.affiliation: Department of Biochemistry, University of Helsinki, Finland.
authors.forename: G
authors.initials: G
authors.lastname: Sievers
authors.forename: H
authors.initials: H
authors.lastname: Häkli
authors.forename: J
authors.initials: J
authors.lastname: Luhtala
authors.forename: R
authors.initials: R
authors.lastname: Tenhunen
mesh_terms: D001120:Arginine / Q000627:therapeutic use; D004578:Electron Spin Resonance Spectroscopy; D006418:Heme / Q000627:therapeutic use; D006801:Humans; D008433:Mathematics; D008970:Molecular Weight; D011164:Porphyrias / Q000188:drug therapy*
chemical_list: D006418:Heme; D001120:Arginine; C048849:heme arginate