Efficient photodissociation of O2 from synthetic heme and heme/M (M = Fe, Cu) complexes.
Single wavelength excitation (lambdaex = 355 or 532 nm) of low-temperature stabilized (198 K) synthetic heme-dioxygen and heme-dioxygen/M complexes, where M = copper or iron in a non-heme environment, results in the dissociation of dioxygen as indicated by the generation of the ferrous heme (Soret band, 427 nm) and the bleaching of the ferric-superoxide (FeIII(O2-)) 410-nm Soret band in the transient absorption difference spectrum. Dioxygen rebinds to the four heme complexes studied with comparable rate constants ( approximately 6-9 x 105 M-1 s-1). However, the quantum yield for complete dissociation of O2 from our simplest heme-O2 complex (F8)FeIII(O2-) (phi = 0.60) is higher than the other complexes measured (phi = approximately 0.2-0.3) as well as that for oxy-myoglobin (phi = 0.3).
Fry
H Christopher
HC
Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
Hoertz
Paul G
PG
Wasser
Ian M
IM
Karlin
Kenneth D
KD
Meyer
Gerald J
GJ
D003300:Copper / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry*; D006418:Heme / Q000031:analogs & derivatives* / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D010777:Photochemistry; D011789:Quantum Theory
D005296:Ferrous Compounds; D006418:Heme; D003300:Copper; D010100:Oxygen