Amino acid adsorption on smectite is relevant to prebiotic processes involving possible catalytic reactions in the early Solar System, as implied by the clay-organic correlation found in meteorites, and the generation and modification of organic components essential for the origin of life. Here we report the results of a study investigating the adsorption of l-lysine (0.025–0.4 M) onto montmorillonite. The reaction products were studied using X-ray diffraction, chemical analysis and infrared spectroscopy.We find that lysine adsorption is first dominated by cation exchange and then by adsorption of electrically neutral lysine (as a zwitterion), as indicated by chemical and FTIR evidence. At the maximum concentration, lysine displaces only ∼1/3 of the original interlayer cations. The d-spacing of the smectite–lysine complex increases from 1.2 to 2.1 nm as more lysine enters the interlayer space, and water is expelled. We propose a structural model of lysine sorption in the interlayer in which lysine is oriented at >45–90◦ to the plane of siloxane O atoms.

Item Type:	Refereed Article
Keywords:	lysine, smectite, amino acid, origin of life
Research Division:	Earth Sciences
Research Group:	Geology
Research Field:	Geology not elsewhere classified
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the earth sciences
UTAS Author:	Parbhakar, A (Dr Anita Parbhakar-Fox)
ID Code:	100616
Year Published:	2007
Web of Science® Times Cited:	66
Deposited By:	Earth Sciences
Deposited On:	2015-05-22
Last Modified:	2015-09-07
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