Investigations of ferric heme cyanide photodissociation in myoglobin and horseradish peroxidase.

ABSTRACT: The photodissociation of cyanide from ferric myoglobin (MbCN) and horseradish peroxidase (HRPCN) has definitively been observed. This has implications for the interpretation of ultrafast IR (Helbing et al. Biophys. J. 2004, 87, 1881-1891) and optical (Gruia et al. Biophys. J. 2008, 94, 2252-2268) studies that had previously suggested the Fe-CN bond was photostable in MbCN. The photolysis of ferric MbCN takes place with a quantum yield of ~75%, and the resonance Raman spectrum of the photoproduct observed in steady-state experiments as a function of laser power and sample spinning rate is identical to that of ferric Mb (metMb). The data are quantitatively analyzed using a simple model where cyanide is photodissociated and, although geminate rebinding with a rate of kBA ≈ (3.6 ps)(-1) is the

SUBMITTER: Zeng W 

PROVIDER: S-EPMC3631277 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature