Issue 24, 2013

Structural specificity of alkoxy radical formation in crystalline carbohydrates


A DFT study of radiation induced alkoxy radical formation in crystalline α-L-rhamnose has been performed to better understand the processes leading to selective radical formation in carbohydrates upon exposure to ionizing radiation at low temperatures. The apparent specificity of radiation damage to carbohydrates is of great interest for understanding radiation damage processes in the ribose backbone of the DNA molecule. Alkoxy radicals are formed by deprotonation from hydroxyl groups in oxidized sugar molecules. In α-L-rhamnose only one alkoxy radical is observed experimentally even though there are four possible sites for alkoxy radical formation. In the present work, the origin of this apparently specific action of radiation damage is investigated by computationally examining all four possible deprotonation reactions from oxygen in the oxidized molecule. All calculations are performed in a periodic approach and include estimates of the energy barriers for the deprotonation reactions using the Nudged Elastic Band (NEB) method. One of the four possible radical sites is ruled out due to the lack of a suitable proton acceptor. For the other three possible sites, the reaction paths and energy profiles from primary cationic radicals to stable, neutral alkoxy radicals are compared. It is found that deprotonation from one site (corresponding to the experimentally observed radical) differs from the others in that the reaction path is less energy demanding. Hence, it is suggested that the alkoxy radical formation is not necessarily site specific, but that the observed radical is formed in much greater abundance than the others due to the different energetics of the processes and reaction products.

Graphical abstract: Structural specificity of alkoxy radical formation in crystalline carbohydrates

Supplementary files

Article information

Article type
21 Feb 2013
19 Apr 2013
First published
22 Apr 2013
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2013,15, 9615-9619

Structural specificity of alkoxy radical formation in crystalline carbohydrates

S. G. Aalbergsjø, E. Pauwels, H. De Cooman, E. O. Hole and E. Sagstuen, Phys. Chem. Chem. Phys., 2013, 15, 9615 DOI: 10.1039/C3CP50789K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity