Americium

Runde, Wolfgang; Schulz, W.W.

doi:10.1007/1-4020-3598-5_8

Cited by 26 publications

(7 citation statements)

References 309 publications

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“…The binding of LanM to Am 3+ was also tested under acidic conditions, since transuranic wastes derived from nuclear fuel reprocessing activities are often acidic. Upon acidification of a Am 3 LanM sample, no significant change is observed for the 5f → 5f absorbance band until about pH 3; at pH below 3, the absorbance bands shift to 503.2 nm (Figure C), consistent with spectra previously reported for uncomplexed Am 3+ in acidic media. , Fitting of the spectral variations at three different wavelengths using the Hill equation (Figure D) yields a pH 1/2 value of 2.79 ± 0.02. The absorbance spectra in the region that corresponds to the protein (<350 nm; Figure S1) also show that LanM releases the metal below pH 3, which is consistent with the changes observed for the americium-specific absorbance band.…”

Section: Resultssupporting

confidence: 85%

“…The absorbance spectra in the protein-specific region also corroborate the fact than LanM competes with small synthetic ligands such as EDTA. As the stability constant of [AmEDTA] − is known (log β 11 = 16.9, at I = 0.1, the same ionic strength at which our experiments were performed), , fitting of the spectrophotometric data in the three spectral windows allows determination of the formation constant for Am 3 LanM. The experiments were performed with the untagged, wild-type protein (LanM) as well as with a version that includes a C-terminal hexahistidine tag ( His LanM – see the Materials section of the Methods), so that log β 31 and K d values could be directly compared with those previously characterized for Ln 3 His LanM complexes. , A log β 31 value of 35.6 ± 0.5 was obtained for Am 3 LanM at pH 5.0, while a value of 34.0 ± 0.5 was obtained for the His LanM variant.…”

Section: Resultsmentioning

confidence: 99%

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Characterization of Americium and Curium Complexes with the Protein Lanmodulin: A Potential Macromolecular Mechanism for Actinide Mobility in the Environment

et al. 2021

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Anthropogenic radionuclides, including long-lived heavy actinides such as americium and curium, represent the primary long-term challenge for management of nuclear waste. The potential release of these wastes into the environment necessitates understanding their interactions with biogeochemical compounds present in nature. Here, we characterize the interactions between the heavy actinides, Am3+ and Cm3+, and the natural lanthanide-binding protein, lanmodulin (LanM). LanM is produced abundantly by methylotrophic bacteria, including Methylorubrum extorquens, that are widespread in the environment. We determine the first stability constant for an Am3+-protein complex (Am3LanM) and confirm the results with Cm3LanM, indicating a ∼5-fold higher affinity than that for lanthanides with most similar ionic radius, Nd3+ and Sm3+, and making LanM the strongest known heavy actinide-binding protein. The protein’s high selectivity over 243Am’s daughter nuclide 239Np enables lab-scale actinide-actinide separations as well as provides insight into potential protein-driven mobilization for these actinides in the environment. The luminescence properties of the Cm3+-LanM complex, and NMR studies of Gd3+-LanM, reveal that lanmodulin-bound f-elements possess two coordinated solvent molecules across a range of metal ionic radii. Finally, we show under a wide range of environmentally relevant conditions that lanmodulin effectively outcompetes desferrioxamine B, a hydroxamate siderophore previously proposed to be important in trivalent actinide mobility. These results suggest that natural lanthanide-binding proteins such as lanmodulin may play important roles in speciation and mobility of actinides in the environment; it also suggests that protein-based biotechnologies may provide a new frontier in actinide remediation, detection, and separations.

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Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Characterization of Americium and Curium Complexes with the Protein Lanmodulin: A Potential Macromolecular Mechanism for Actinide Mobility in the Environment

et al. 2021

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“…The linear, hexavalent actinyl ions, {O=An VI =O} 2+ , are important in solution chemistry of U [2], Np [3] and Pu [4]. The americyl ion, Am VI O 2 2+ , is a stable species in solution but is not predominant under most conditions [5]. The uranyl ion is particularly prevalent and has been extensively studied by both experiment and theory [6].…”

Section: Introductionmentioning

confidence: 99%

Gas-Phase Coordination Complexes of U^VIO₂²⁺, Np^VIO₂²⁺, and Pu^VIO₂²⁺ with Dimethylformamide

Rutkowski

Ríos

Gibson

et al. 2011

J. Am. Soc. Mass Spectrom.

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“…This potential is exemplified in the established relationship between the number of coordination sites on a chelating agent and the binding of 241 Am. 32 The tri-ethyl ester of DTPA, with five coordination sites, represents the DTPA intermediate in the urine with the fewest number of coordination sites. According to this relationship, it may still possess a high affinity for 241 Am with a stability constant of approximately 10 15 M −1 .…”

Section: Discussionmentioning

confidence: 99%

Orally Administered DTPA Penta-Ethyl Ester for the Decorporation of Inhaled 241Am

Sueda

Sadgrove

Huckle

et al. 2014

Journal of Pharmaceutical Sciences

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Diethylenetriaminepentaacetic acid (DTPA) is an effective decorporation agent to facilitate the elimination of radionuclides from the body, but its permeability-limited oral bioavailability limits its utility in mass-casualty emergencies. To overcome this limitation, a prodrug strategy using the penta-ethyl ester form of DTPA is under investigation. Pharmacokinetic and biodistribution studies were conducted in rats by orally administering [14C]DTPA penta-ethyl ester, and this prodrug and its hydrolysis products were analyzed as a single entity. Compared to a previous reporting of intravenously administered DTPA, the oral administration of this prodrug resulted in a sustained plasma concentration profile with higher plasma exposure and lower clearance. An assessment of the urine composition revealed that the bioactivation was extensive but incomplete, with no detectable levels of the penta- or tetra-ester forms. Tissue distribution at 12 h was limited, with approximately 73% of the administered dose being associated with the gastrointestinal tract. In the efficacy study, rats were exposed to aerosols of 241Am nitrate before receiving a single oral treatment of the prodrug. The urinary excretion of 241Am was found to be 19% higher than with the control. Consistent with prior reports of DTPA, the prodrug was most effective when the treatment delays were minimized.

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Americium

Cited by 26 publications

References 309 publications

Characterization of Americium and Curium Complexes with the Protein Lanmodulin: A Potential Macromolecular Mechanism for Actinide Mobility in the Environment

Characterization of Americium and Curium Complexes with the Protein Lanmodulin: A Potential Macromolecular Mechanism for Actinide Mobility in the Environment

Gas-Phase Coordination Complexes of U^VIO₂²⁺, Np^VIO₂²⁺, and Pu^VIO₂²⁺ with Dimethylformamide

Orally Administered DTPA Penta-Ethyl Ester for the Decorporation of Inhaled 241Am

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Americium

Cited by 26 publications

References 309 publications

Characterization of Americium and Curium Complexes with the Protein Lanmodulin: A Potential Macromolecular Mechanism for Actinide Mobility in the Environment

Characterization of Americium and Curium Complexes with the Protein Lanmodulin: A Potential Macromolecular Mechanism for Actinide Mobility in the Environment

Gas-Phase Coordination Complexes of UVIO22+, NpVIO22+, and PuVIO22+ with Dimethylformamide

Orally Administered DTPA Penta-Ethyl Ester for the Decorporation of Inhaled 241Am

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Gas-Phase Coordination Complexes of U^VIO₂²⁺, Np^VIO₂²⁺, and Pu^VIO₂²⁺ with Dimethylformamide