Understanding selenocysteine through conformational analysis, proton affinities, acidities and bond dissociation energies

Density functional methods have been employed to characterize the gas phase conformations of selenocysteine. The 33 stable conformers of selenocysteine have been located on the potential energy surface using density functional B3LYP/6‐31+G* method. The conformers are analyzed in terms of intramolecular hydrogen bonding interactions. The proton affinity, gas phase acidities, and bond dissociation energies have also been evaluated for different reactive sites of selenocysteine for the five lowest energy conformers at B3LYP/6‐311++G*//B3LYP/6‐31+G* level. Evaluation of these intrinsic properties reflects the antioxidant activity of selenium in selenocysteine.