Alloenzyme

Alloenzymes are common biological enzymes that exhibit high levels of functional evolutionary conservation throughout specific phylas and kingdoms. They are used by phylogeneticists as molecular markers to gauge evolutionary histories and relationships between different species of organisms.

These enzymes generally perform very basic functions found commonly throughout all lifeforms, such as DNA polymerase, the enzyme that repairs and copies DNA. Significant changes in this enzyme reflect significant events in evolutionary history of organisms. As expected DNA polymerase shows relatively small differences in its amino acid sequence between phyla and even kingdoms.

The key to choosing which alloenzyme to use in a comparison between multiple species is by choosing one that is as variable as possible while still being present in all the organisms. By comparing the amino acid sequence of the enzyme in the species, more amino acid similarities should be seen between evolutionarily related species and fewer between those that are less well related. The less well conserved the enzyme is, the more amino acid differences will be present in even closely related species.

ee also

*Comparative genomics
*Phylogenetics
*Molecular phylogeny
*Molecular evolution
*Homology (biology)