Degradation of amino acids on Mars by UV irradiation in the presence of chloride and oxychlorine salts
File(s)
Accepted version
Author(s)
Liu, Dongyu
Kounaves, Samuel P
Type
Journal Article
Abstract
The degradation of glycine (Gly), proline (Pro), and tryptophan (Trp) was studied under simulated Mars conditions during UV-driven production of oxychlorines and compared under Mars ambient and humid conditions, as films, and with addition of sodium chloride (NaCl), sodium chlorate (NaClO3), and sodium perchlorate (NaClO4) salts. It was shown that glycine sustained no significant destruction in either of the non-salt samples under Mars ambient or humid conditions. However, its degradation increased in the presence of any of the three salts and under both conditions though more under humid conditions. Proline degradation followed the order No Salt > NaCl > NaClO3 > NaClO4 under Mars ambient conditions but the reverse order under Mars humid conditions. A mechanism is proposed to explain how water and silica participate in these degradation reactions and how it is strongly influenced by the identity of the salt and its ability to promote deliquescence. No difference was observed for tryptophan between Mars ambient and humid conditions, or for the different salts, suggesting its degradation mechanism is different compared to glycine and proline. The results reported here will help to better understand the survival of amino acids in the presence of oxychlorines and UV on Mars and thus provide new insights for the detection of organic compounds on future Mars missions.
Date Issued
2021-07-06
Date Acceptance
2021-02-27
Citation
Astrobiology, 2021, 21 (7), pp.793-801
ISSN
1531-1074
Publisher
Mary Ann Liebert
Start Page
793
End Page
801
Journal / Book Title
Astrobiology
Volume
21
Issue
7
Copyright Statement
© 2021, Mary Ann Liebert, Inc., publishers.
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/33787313
Subjects
Amino acids. Astrobiology 21, xxx–xxx
Mars
Oxychlorines
Perchlorate
UV
Publication Status
Published
Coverage Spatial
United States
Date Publish Online
2021-03-30