skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: New structural insights into the iron-molybdenum cofactor from azotobacter vinelandii nitrogenase through sulfur K and molybdenum L x-ray absorption edge studies

Abstract

The electronic and structural nature of sulfur and molybdenum in the FeMO cofactor (FeMO-co) isolated from Azotobacter vinelandii MoFe protein has been studied by X-ray absorption edge and near-edge spectroscopy (referred to herein collectively as XANES) at the sulfur K and molybdenum L/sub 3/ and L/sub 2/ absorption edges. In contrast to the relatively poor resolution found for X-ray absorption edges at higher energies (e.g., several electronvolts at the molybdenum K edge at 20 keV), resolution in the 2.5-3.0-keV region is significantly improved (e.g., 0.5 eV at the sulfur K edge at 2.47 keV), resulting in more edge structure with higher sensitivity to changes in electronic and structural environment. In order to record spectra from dilute samples at these low energies, an experimental method that takes advantage of the higher flux synchrotron radiation from an undulator magnet has been developed. XANES spectra have been recorded for FeMo-co in the oxidized (ox) and semireduced (s-r) forms and, for comparison, a number of inorganic complexes containing molybdenum and sulfur. To remove the interference of dithionite, its decomposition products, and other small, unbound molecules from the FeMo-co spectrum, an anaerobic column chromatographic method of purification has been developed. The spectrum of dithionite-free FeMo-comore » in the oxidized form could thus be recorded.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Stanford Synchrotron Radiation Lab., CA (USA)
OSTI Identifier:
7003566
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Am. Chem. Soc.; (United States); Journal Volume: 110:12
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; NITROGENASE; ELECTRONIC STRUCTURE; ABSORPTION SPECTROSCOPY; AZOTOBACTER; EXPERIMENTAL DATA; IRON; MOLYBDENUM; PROTEINS; X RADIATION; BACTERIA; DATA; ELECTROMAGNETIC RADIATION; ELEMENTS; ENZYMES; INFORMATION; IONIZING RADIATIONS; METALS; MICROORGANISMS; NITRO-GROUP DEHYDROGENASES; NUMERICAL DATA; ORGANIC COMPOUNDS; OXIDOREDUCTASES; RADIATIONS; SPECTROSCOPY; TRANSITION ELEMENTS; 400201* - Chemical & Physicochemical Properties

Citation Formats

Hedman, B., Frank, P., Gheller, S.F., Roe, A.L., Newton, W.E., and Hodgson, K.O.. New structural insights into the iron-molybdenum cofactor from azotobacter vinelandii nitrogenase through sulfur K and molybdenum L x-ray absorption edge studies. United States: N. p., 1988. Web. doi:10.1021/ja00220a013.
Hedman, B., Frank, P., Gheller, S.F., Roe, A.L., Newton, W.E., & Hodgson, K.O.. New structural insights into the iron-molybdenum cofactor from azotobacter vinelandii nitrogenase through sulfur K and molybdenum L x-ray absorption edge studies. United States. doi:10.1021/ja00220a013.
Hedman, B., Frank, P., Gheller, S.F., Roe, A.L., Newton, W.E., and Hodgson, K.O.. Wed . "New structural insights into the iron-molybdenum cofactor from azotobacter vinelandii nitrogenase through sulfur K and molybdenum L x-ray absorption edge studies". United States. doi:10.1021/ja00220a013.
@article{osti_7003566,
title = {New structural insights into the iron-molybdenum cofactor from azotobacter vinelandii nitrogenase through sulfur K and molybdenum L x-ray absorption edge studies},
author = {Hedman, B. and Frank, P. and Gheller, S.F. and Roe, A.L. and Newton, W.E. and Hodgson, K.O.},
abstractNote = {The electronic and structural nature of sulfur and molybdenum in the FeMO cofactor (FeMO-co) isolated from Azotobacter vinelandii MoFe protein has been studied by X-ray absorption edge and near-edge spectroscopy (referred to herein collectively as XANES) at the sulfur K and molybdenum L/sub 3/ and L/sub 2/ absorption edges. In contrast to the relatively poor resolution found for X-ray absorption edges at higher energies (e.g., several electronvolts at the molybdenum K edge at 20 keV), resolution in the 2.5-3.0-keV region is significantly improved (e.g., 0.5 eV at the sulfur K edge at 2.47 keV), resulting in more edge structure with higher sensitivity to changes in electronic and structural environment. In order to record spectra from dilute samples at these low energies, an experimental method that takes advantage of the higher flux synchrotron radiation from an undulator magnet has been developed. XANES spectra have been recorded for FeMo-co in the oxidized (ox) and semireduced (s-r) forms and, for comparison, a number of inorganic complexes containing molybdenum and sulfur. To remove the interference of dithionite, its decomposition products, and other small, unbound molecules from the FeMo-co spectrum, an anaerobic column chromatographic method of purification has been developed. The spectrum of dithionite-free FeMo-co in the oxidized form could thus be recorded.},
doi = {10.1021/ja00220a013},
journal = {J. Am. Chem. Soc.; (United States)},
number = ,
volume = 110:12,
place = {United States},
year = {Wed Jun 08 00:00:00 EDT 1988},
month = {Wed Jun 08 00:00:00 EDT 1988}
}