Abstract: We studied  the mechanism of the reaction between 2α-Ala→Mg²⁺ (bis-alanine chelating magnesium)  and  ^.OH (hydroxyl radical) in the aqueous phase environment of living organisms (1.013×10⁵ Pa,  310.15 K) at the level of M06-2X/6-311+G(d,p)//MN15/6-311++G(3df,2pd)  theory, and investigated two reaction channels of  2α-Ala→Mg²⁺ and ^.OH for the hydrogen abstraction and addition. The calculation results show   that the energy barrier for the hydrogen abstraction reaction is from 20.1 to 62.3 kJ/mol,  all of which are exothermic reactions. The energy barrier for the addition reaction is from 65.7 to 70.9 kJ/mol,  with a slight endothermic reaction. Therefore,  2α-Ala→Mg²⁺ in living organisms can easily scavenge ^.OH by abstracting H atoms.

Key words: bis-alanine chelating magnesium,  , hydroxyl radical,  ,  , self-consistent reaction field theory,  , density functional theory, free energy barrier