On the photosensitivity of liganded hemoproteins and their metal-substituted analogues.

AUTOR(ES)

Hoffman, B M

RESUMO

We have examined the photosensitivity of low-spin liganded hemoglobin, myoglobin, and peroxidase, and their metal-substituted analogues, using three different metals (Fe, Mn, Co) in several oxidation states and employing a variety of diatomic or pseudo-diatomic ligands (L). We have discovered a number of photosensitive systems, and present an overall stereo-electronic classification scheme for these photodissociation reactions: Linear, formally d6, metal-ligand fragments [e.g., Fe(II) +/- CO; Mn(II) +/- NO] are relatively photoliable, but systems with a bent fragment, and higher electron occupancy [e.g., Fe(II) +/- O2; Co(II) +/- NO] are relatively photoinert. Photostability appears to correlate with the occurrence of long-wavelength features in the optical absorption spectra, and the classification scheme is explained by considerations of electronic structure. The discussions are further applied to d5 systems and to low-spin d6 metalloporphyrins with nitrogenous bases as axial ligands.

Documentos Relacionados

• Triplet state magnetic resonance and fluorescence spectroscopy of metal-substituted hemoglobins.
• Acetylpolyamine amidohydrolase from Mycoplana ramosa: gene cloning and characterization of the metal-substituted enzyme.
• The antiviral activity of tetrazole phosphonic acids and their analogues.
• Mechanisms for the solvolytic decompositions of nucleoside analogues. X. Acidic hydrolysis of 6-substituted 9-(beta-D-ribofuranosyl)purines.
• The reversible DNA-alkylating activity of duocarmycin and its analogues.