Femtosecond photolysis of CO-ligated protoheme and hemoproteins: appearance of deoxy species with a 350-fsec time constant.
Year: 1983
Type: article
Abstract: Photolysis of HbCO, MbCO, and CO-protoheme has been investigated by measuring transient differential spectra and kinetics of induced absorption after excitation with a 250-fsec laser pulse at 307 nm. Probing was performed by a part of a continuum pulse between 395 and 445 nm. Photodissociation of the three liganded species occurred within the pulse duration. By contrast, the formation of deoxy species appeared with a mean (+/- SD) response time of 350 +/- 50 fsec. This time constant was identical for the three species and independent of the presence or absence of the protein structure. Our results suggest the formation of a transient high-spin in plane iron (II) species which relaxes in 350 fsec to a high-spin stable state with concerted kinetics of CO departure and iron displacement. The spin transition is suspected to occur via liganded excited states which relax in part to non-reactive states with a 3.2-psec time constant.
Authors: J L Martin, A Migus, C Poyart, Y Lecarpentier, R Astier, A Antonetti
Language: English
Subfield: Cell Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W1976404178