Gradient bundle analysis of ketosteroid isomerase

Bond bundle analysis is used to investigate enzymatic catalysis in the KSI active site. We calculate the precise redistribution of electron charge density and other property fields, between atoms and bonds, that accompanies enhancement (and inhibition) of the catalytic activity. In two examples—direct inspection of bond bundle regional properties, and correlation between those properties and reaction barrier height—we arrive at similar conclusions, that catalytic enhancement is the result of moving electron density between bonds in a way that closely resembles our mechanistic understanding of the catalyzed reaction.