Determination of the geometric and electronic structure of activated bleomycin using X-ray absorption spectroscopy

Journal Article · Wed Feb 01 04:00:00 EST 1995 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00109a014· OSTI ID:6455712

Westre, T E; Loeb, K E; Zaleski, J M; Hedman, B; Hodgson, K O; Solomon, E I ^[1]

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1. 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), Journal Name: Journal of the American Chemical Society; (United States) Vol. 117:4; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400201* -- Chemical & Physicochemical Properties
ABSORPTION SPECTROSCOPY
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
ANTIMITOTIC DRUGS
ANTINEOPLASTIC DRUGS
BLEOMYCIN
CHEMICAL ACTIVATION
CHEMICAL BONDS
COMPLEXES
DRUGS
ELECTRONIC STRUCTURE
IRON COMPLEXES
REACTION INTERMEDIATES
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
TRANSITION ELEMENT COMPLEXES
X-RAY SPECTROSCOPY