| Abstract: | Most intracellular enzymes are made up of several identical or different subunits. The more remote any two organisms are phylogenetically, the greater will be the differences in amino acid sequence of a given enzyme. Nevertheless, numerous examples exist of specific association between chemically different subunits, or even of the formation of enzyme chimeras. They span not only the boundaries between related organisms but also the deep rift between prokaryotic and eukaryotic cells. Exchange of subunits between enzymes of similar activity but differing origin can be rationalized by assuming enzymes to posses functionally defined types of three-dimensional structures. |
