Glutamyl-glutamate – a tailor-made chelating ligand for the [Be4O]6+ core in basic beryllium complexes and implications on investigations on the origins of chronic beryllium disease

Abstract

Abstract Density functional theory calculations suggest that l-glutamyl-l-glutamate [H-Glu-Glu-H]2– can act as an efficient chelating ligand in basic beryllium carboxylates of type Be4O(RCO2)6. An exergonic energy balance of –10.6 kcal mol–1 for the substitution of two [AcO]– anions by one [H-Glu-Glu-OH]2– dianion in Be4O(AcO2)6 has been calculated; for a second and third substitutions, the computed energy release amounts to –9.3, and –11.3 kcal mol–1. The coordination geometry of the complexes shows a trend toward less deviation from local octahedral symmetry with increasing number of [H-Glu-Glu-OH]2– ligands. The implications of these findings for the yet unknown molecular origins of chronic beryllium disease (CBD) are discussed, and a Be4O moiety is suggested as the beryllium species engaged in CBD.