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Martian Superoxide and Peroxide O2 Release (OR) Assay: A New Technology for Terrestrial and Planetary ApplicationsThis study presents an assay for the detection and quantification of soil metal superoxides and peroxides in regolith and soil. The O2 release (OR) assay is based on the enzymatic conversion of the hydrolysis products of metal oxides to O2, and their quantification by an O2 electrode based on the stoichiometry of the involved reactions: The intermediate product O2 from the hydrolysis of metal superoxides is converted by cytochrome c to O2, and also by superoxide dismutase (SOD) to 1/2 mol O2 and 1/2 mol H2O2, which is then converted by catalase (CAT) to 1/2 mol O2. The product H2O2 from the hydrolysis of metal peroxides and hydroperoxides is converted to 1/2 mol O2 by CAT. The assay-method was validated in a sealed sample chamber using a liquid-phase Clark-type O2 electrode with known concentrations of O2 and H2O2, and with commercial metal superoxide and peroxide mixed with Mars analogue Mojave and Atacama Desert soils. Carbonates and perchlorates, both present on Mars, do not interfere with the assay. The assay lower limit of detection, using luminescence quenching/optical sensing O2-electrodes, is 1 nmol O2 cm(exp. -3) or better. The activity of the assay enzymes SOD and cytochrome c was unaffected up to 6 Gy exposure by gamma-radiation, while CAT retained 100% and 40% of its activity at 3 and 6 Gy, respectively, demonstrating the suitability of these enzymes for planetary missions, e.g., in Mars or Europa.
Document ID
20160000582
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Georgiou, Christos D.
(Patras Univ. Greece)
Zisimopoulos, Dimitrios
(Patras Univ. Greece)
Panagiotidis, Konstantinos
(Patras Univ. Greece)
Grintzalis, Kontantinos
(Patras Univ. Greece)
Papapostolou, Ioannis
(Patras Univ. Greece)
Quinn, Richard C.
(Search for Extraterrestrial Intelligence Inst. Moffett Field, CA, United States)
McKay, Christopher P.
(NASA Ames Research Center Moffett Field, CA, United States)
Sun, Henry J.
(Desert Research Inst. Reno, NV, United States)
Date Acquired
January 11, 2016
Publication Date
January 1, 2015
Subject Category
Lunar And Planetary Science And Exploration
Inorganic, Organic And Physical Chemistry
Report/Patent Number
ARC-E-DAA-TN27477
Funding Number(s)
CONTRACT_GRANT: NNX12AG91A
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
soil metal superoxides and peroxides
Mars analogue Mojave and Atacama Desert soils
O2 release (OR) assay
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