Relative strengths of Se•••N,O interactions:: Implications for glutathione peroxidase activity

Natural bond orbital (NBO) studies of model compounds of glutathione peroxidase and its mimics are used to examine the relative strengths of nitrogen and oxygen donor groups in simple models and omega-substituted selenenic acids. Nitrogen-containing groups are generally better donors, but the weak Lewis basicity of the amide nitrogen allows for preferential interaction with the carbonyl oxygen which suggests that the glutamine of the GPX catalytic triad influences activity through an Se center dot center dot center dot O interaction. (c) 2005 Elsevier B.V. All rights reserved.