The Role of Inhibition in Enzyme Evolution

Most people believe that new enzymes evolve from existing enzymes because of the conservation of amino acid sequence and tertiary structures in enzymes with different functions and the low probability that such similarities could evolve independently. However, the process by which this divergence occurs is still debatable. A reasonable proposal for this process is the duplication of a gene encoding an existing enzyme, accumulation of mutations in the gene duplicate(s) with consequential functional divergence, followed by selection for an enzyme with a new function [1]. To substantiate this proposal, several areas must be addressed. Which proteins serve as templates? Under what conditions would this series of events occur? What selective advantage does a new enzyme confer upon the host?