Oxidative stress is a physiological condition resulting from overproduction of reactive oxygen species (ROS) and reactive nitrogen species (RNS), which damage biological structures such as lipids in membranes, DNA, and protein.  Oxidative stress is linked to the pathogenesis of many diseases and aging. Non-covalent interactions govern structure and function in biological molecules.  The major question we address is how oxidative stress alters the non-covalent interactions in beta structures.  Open-shell ROS and RNS species initiate oxidative damage pathways via a hydrogen abstraction reaction.  A tri-alanine peptide in a �-strand and �-turn conformation is used to model the hydrogen abstraction reaction:  �OH + AAA ?HOH + AAA�.  Open-shell pairwise interaction energy decomposition analysis (OS-PIEDA) is used to quantify the non-covalent interactions in the �-structures before and after hydrogen abstraction.  The OS-PIEDA method allows analysis for inter- and intramolecular interactions in terms of electrostatic, exchange repulsion, charge transfer, dispersion and optional polarization energies for molecular systems with a radical.  Depending on the hydrogen abstraction site, terminal interactions in the �-turn may become weaker or stronger, and often change the character of the non-covalent bonding from amide stacking to hydrogen bonding.

Oxidative stress alters non-covalent interactions in �-structures

246th National Meeting (2013)

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