Exploring Post-Translational Modification with DFT

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Virtual Inorganic Pedagogical Electronic Resource


This activity is designed to give students a deeper understanding of what post-translational modification does in a metalloenzyme using nitrile hydratase (NHase) as a model system. The metallo-active site of NHase contains a cobalt(III) center that is bound to an unusual coodination sphere containing bis-amidate, cysteinate, sulfenate (RSO-), and sulfinate (RSO2-) ligands. Using density functional theory calculations on a simple model of the coordination environment of the cobalt, students will carry out geometry optimizations on three compounds that have either a sulfide, sulfenate, or sulfinate ligand. The students will compare the partial atomic charges on sulfur in the three cases and compare them to their predicted atomic charges based on oxidation number.