Determination of the geometric and electronic structure of activated bleomycin using X-ray absorption spectroscopy
- Stanford Univ., CA (United States)
Activated Bleomycin (BLM) is the first mononuclear non-heme iron oxygen intermediate stable enough for detailed spectroscopic study. DNA degradation by activated BLM involves C-H bond cleavage at the C4[prime] position of deoxyribose moieties and results in the production of base propenals. It has been postulated that activated BLM is an oxo-ferryl intermediate on the basis of its reactivity and analogy with cytochrome P-450 chemistry. Alternatively, spectroscopic and model studies have indicated activated BLM to have an iron(III)-peroxide site. In this study, X-ray absorption spectroscopy (XAS) has been used to directly probe the oxidation and spin states of the iron in activated BLM and to determine if a short iron-oxo bond is present, which would be characteristic of the oxo-ferryl species of heme iron. Both the pre-edge and edge regions of the Fe K-edge spectra indicate that activated BLM is a low spin ferric complex. The pre-edge intensity of activated BLM is also similar to that of low spin ferric BLM and does not show the intensity enhancement which would be present if there were a short Fe-O bond. Furthermore, bond distances obtained from EXAFS are similar to those in low spin Fe[sup III]BLM and show no evidence for a short iron-oxo bond. 33 refs., 4 figs., 1 tab.
- OSTI ID:
- 6455712
- Journal Information:
- Journal of the American Chemical Society; (United States), Vol. 117:4; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BLEOMYCIN
CHEMICAL ACTIVATION
IRON COMPLEXES
ABSORPTION SPECTROSCOPY
ELECTRONIC STRUCTURE
X-RAY SPECTROSCOPY
CHEMICAL BONDS
REACTION INTERMEDIATES
STRUCTURAL CHEMICAL ANALYSIS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
ANTIMITOTIC DRUGS
ANTINEOPLASTIC DRUGS
COMPLEXES
DRUGS
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
400102 - Chemical & Spectral Procedures