Allozyme

An allozyme is a variant form of an enzyme that differs from other allozymes of the same enzyme due to genetic variation, specifically at the allele level. Enzymes are proteins that catalyze biochemical reactions, and their structure and function are determined by the genes that encode them. Different alleles of a gene can lead to slightly different amino acid sequences in the resulting enzyme. These structural differences, even if minor, can sometimes result in variations in the enzyme's electrophoretic mobility or catalytic activity.

The study of allozymes has been historically significant in population genetics and evolutionary biology. By examining the frequencies of different allozymes within a population, researchers can infer genetic diversity, population structure, and patterns of gene flow. Because allozymes are codominantly inherited, meaning both alleles in a heterozygote are expressed and detectable, they can be readily studied using gel electrophoresis. This technique separates proteins based on their size and electrical charge.

Allozymes have been instrumental in understanding the genetic basis of adaptation and speciation. While many allozymic variations are neutral, some can affect fitness by altering enzyme efficiency under specific environmental conditions. The relative ease of assay and interpretation made allozymes a workhorse for genetic studies for several decades, particularly before the widespread adoption of DNA-based molecular markers. Although largely superseded by DNA sequencing and other genomic techniques, the principles learned from allozyme studies continue to inform modern evolutionary and ecological research.