Allozyme

Definition

An enzyme variant encoded by different alleles at the same genetic locus, detectable as distinct electrophoretic mobilities due to amino-acid substitutions that alter net charge or conformation without necessarily changing catalytic function. Allozymes serve as codominant Mendelian markers for estimating heterozygosity, gene flow, and population structure in natural populations.

Etymology

From Greek allos (other, different) + enzyme

Example

In a study of bark beetle (Dendroctonus ponderosae) population genetics, researchers screened five allozyme loci to detect cryptic gene flow across mountain ranges that morphological characters could not resolve.

Synonyms

• alloenzyme

Related Terms

• Isozyme
• Allele
• Electrophoresis
• heterozygosity
• Genetic marker
• population genetics
• microsatellite

Usage Notes

Contrast with isozymes: allozymes arise from allelic variation at one locus, whereas isozymes are products of different gene loci (e.g., tissue-specific lactate dehydrogenase isozymes). In arthropod studies, allozyme electrophoresis has been largely superseded by DNA-based markers, but remains useful for historical datasets and rapid, low-cost screening of preserved specimens. The term is sometimes used loosely for any electrophoretically separable enzyme variant; strict usage reserves it for allelic variants.