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Photoabsorption Study of Bacillus megaterium, DNA and Related Biological Materials in the Phosphorus K-edge RegionWe have measured the x-ray transmission spectra of several biologically related samples in the phosphorus K-edge absorption region. These include elemental red phosphorus, hydrated sodium phosphate (Na3PO4.12H2O), deoxyribonucleic acid (DNA), adenosinetriphosphate (ATP), diolylphosphatidyl choline (DOPC), and Bacillus megaterium spores. Elemental red phosphorus essentially displays an edge-jump. All other spectra are similar in form and energy position. Each spectrum for these substances is dominated by a narrower, more intense first peak and a broader but less intense second peak. The corresponding K-edge absorption thresholds are shifted towards higher energy relative to that for elemental red phosphorus, as expected for increasing degrees of phosphorus oxidation. The B. megaterium spectrum has aspects common to both the phosphate and DNA spectra and is therefore interpreted as a composite of spectra arising from DNA/RNA and phosphates within the spore. The B. megaterium spore spectrum provides needed information for resonant radiation damage studies in the phosphorus K-edge absorption region by identifying candidate photoexcitations. In addition,the absorption spectra will be useful in macromolecular crystallography studies employing anomalous dispersion effects at the phosphorus K-edge.
Document ID
20030054440
Acquisition Source
Marshall Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Frigo, Sean P.
(University of Northern Arizona Flagstaff, AZ, United States)
McNulty, Ian
(Argonne National Lab. IL, United States)
Richmond, Robert C.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Ehret, Charles F.
(Ehret (Charles F.) Clarendin Hills, IL, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Subject Category
Atomic And Molecular Physics
Distribution Limits
Public
Copyright
Other

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