Effect of Sodium Dodecyl Sulfate on Spectral Properties of Five- and Six-Coordinate Nitrosyl(protoporphyrin IX dimethyl esterato)iron(II) Complexes

Abstract

Abstract EPR and electronic spectra of five- and six-coordinate nitrosyl(protoporphyrin IX dimethyl esterato)iron(II) (Fe(ppixdme)(NO)) complexes as model systems for nitrosylhemoproteins have been investigated in the absence and the presence of sodium dodecyl sulfate (SDS). Dimethyl sulfoxide, an O-donor ligand, is weakly coordinated to iron in an axial vacant position trans to a nitrosyl group in Fe(ppixdme)(NO). Upon addition of SDS to Fe(ppixdme)(NO) in dimethyl sulfoxide, EPR and electronic spectra were changed into five-coordinate type spectra. On the other hand, the addition of SDS to Fe(ppixdme)(NO)(NMeIm) in dimethyl sulfoxide resulted in EPR and electronic spectra arising from a mixture of five- and six-coordinate complexes. Accordingly, sodium dodecyl sulfate was found to hinder the interaction of dimethyl sulfoxide with the sixth axial vacant position of Fe(ppixdme)(NO), and to cleave only partly the iron to imidazole bond in Fe(ppixdme)(NO)(NMeIm) complex.