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Understanding Ferrichrome Structural Interaction with Uranium Compounds


EMSL Project ID
48595

Abstract

Siderophores are generally low molecular weight iron chelating compounds that are essential for plant and microbial iron acquisition. These compounds are released into the environment to mobilize iron for cellular uptake. These compounds have also been shown to interact with uranium and may play an important role in mobility of these species in soil and wetland environments. This is important . Since uranium is different from iron in the chemical form and solubility at various pH values, it is important to understand how common forms of uranium, such as uranyl, interact with siderophores and the impact of the siderophore structure. In particular, work on siderophore uranyl interactions has exclusively been done on hydroxamate-type siderophores and little is known about how siderophores with both hydroxamate and carboxylate functional groups complex with uranyl ions in solution. Gas-phase mass spectrometry studies indicate that siderophores with carboxylate functional groups have a relatively stronger binding with uranyl ions than do hydroxamate siderophores at lower pH. Tandem mass spectrometry data and molecular modeling calculations show that the hydroxamate functional groups mediate the interaction with uranyl ions. Solution-phase measurements on the structure of both hydroxamate and carboxylate types of siderophores complexed with uranyl ions is needed to better understand this interaction and its dependence on pH. We propose to examine des-ferrichrome (hydroxamate form) and desferrichrome A (mixed hydroxamate and carboxylate groups) in solution with uranyl acetate in two different pH solutions using 1H NMR. This technique has previously been used to examine the interaction of synthetic hydroxamate chelators with uranyl ions. This request will require the use of concentrated solutions of uranyl acetate above the volumetrically releasable limits and therefore we request access to NMR instrumentation in the radiological wing of the EMSL.

Project Details

Project type
Special Science
Start Date
2014-11-01
End Date
2015-09-30
Status
Closed

Team

Principal Investigator

David Wunschel
Institution
Pacific Northwest National Laboratory

Team Members

Morgan Kelley
Institution
Los Alamos National Laboratory