Mechanistically diverse enzyme superfamilies: the importance of chemistry in the evolution of catalysis.

The strategy that nature has used to evolve new catalytic activities from pre-existing enzymes (i.e. retention of substrate binding or of catalytic mechanism) has been controversial. Recent work supports a strategy in which a partial reaction, catalyzed by a progenitor, is retained, and the active-site architecture is modified to allow the intermediate generated to be directed to different products.