Spectroscopic and theoretical description of the electronic structure of the S = 3/2 nitrosyl complex of non-heme iron enzymes

Journal Article · Wed Nov 04 00:00:00 EST 1992 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja00049a062· OSTI ID:569228

Zhang, Yan; Pavlosky, M A; Brown, C A ^[1]

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1. Stanford Univ., CA (United States); and others

Non-heme iron centers are present in the catalytic active sites of a large number of enzymes which are involved in the binding and activation of dioxygen. A member of this class, soybean lipoxygenase (SBL), catalyzes the reaction of 1,4-unsaturated lipids with dioxygen to form a hydroperoxide product. Nitrosyl complexes of enzymes serve as reversible analogues of possible dioxygen intermediates involved in catalysis. SBL-NO and other non-heme ferrous enzyme nitrosyl complexes (formulated as (FeNO){sup 7}) exhibit an unusual S = {sup 3}/{sub 2}{sub 3}EPR signal, which is also observed in (FeNO){sup 7} model complexes. A wide range of bonding descriptions have appeared for these complexes, which include [Fe{sup +}d{sup 7}(S = 3/2)-NO{sup +}(S = O)], [Fe{sup 2+}d{sup 6}(S=2)-NO{sup 0}(S=1/2)] antiferromagnetically coupled, [Fe{sup 3+}d{sup 5}(S =1/2)-NO{sup {minus}}(S = 1)] ferromagnetically coupled, and [Fe{sup 3+}d{sup 5}(S = 3/2)-NO{sup {minus}}(S=0)]. In order for the NO derivative of these enzymes to be used as a probe of electron distribution related to dioxygen reactivity, a clear understanding of the electronic structure and associated spectral features of the S = 3/2 (FeNO){sup 7} unit is required. Spectroscopic techniques and theoretical methods have been used to study SBL-NO and two S = 3/2 ground-state model complexes, FeL-(NO)(N{sub 3}){sub 2}, where L = N,N{prime},N{double_prime}-trimethyl-1,4,7-triazacyclononane and FeEDTA-NO. 20 refs., 2 figs.

• Sponsoring Organization: USDOE
• OSTI ID: 569228
• Journal Information: Journal of the American Chemical Society, Vol. 114, Issue 23; Other Information: PBD: 4 Nov 1992
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
40 CHEMISTRY
COMPLEXES
CHEMICAL BONDS
CATALYSIS
ELECTRONIC STRUCTURE
ACTIVATION ENERGY
RAMAN SPECTRA
STRUCTURAL CHEMICAL ANALYSIS
ENZYMES
QUANTITATIVE CHEMICAL ANALYSIS
ENZYME ACTIVITY
CHEMICAL REACTIONS
REACTION INTERMEDIATES
CHEMICAL REACTION KINETICS
HEME
IRON
LIPIDS
PROBES
RAMAN SPECTROSCOPY