title: Evolution of catalytic proteins or on the origin of enzyme species by means of natural selection.
abstract: It is believed that all present-day organisms descended from a common cellular ancestor. Such a cell must have evolved from more primitive and simpler precursors, but neither their organization nor the route such evolution took are accessible to the molecular techniques available today. We propose a mechanism, based on functional properties of enzymes and the kinetics of growth, which allows us to reconstruct the general course of early enzyme evolution. A precursor cell containing very few multifunctional enzymes with low catalytic activities is shown to lead inevitably to descendants with a large number of differentiated monofunctional enzymes with high turnover numbers. Mutation and natural selection for faster growth are shown to be the only conditions necessary for such a change to have occurred.
mesh_terms: D005075:Biological Evolution; D002455:Cell Division; D002477:Cells / Q000201:enzymology; D004798:Enzymes / Q000235:genetics*; D005784:Gene Amplification; D007700:Kinetics; D008954:Models, Biological; D009154:Mutation; D011506:Proteins / Q000235:genetics; D012641:Selection, Genetic
chemical_list: D004798:Enzymes; D011506:Proteins