Glucoseisomerase

Glucoseisomerase is an enzyme that catalyzes the reversible isomerization of D-glucose to D-fructose. It belongs to the family of aldose–ketose isomerases and relies on a metal ion cofactor to facilitate the isomerization via an enediol intermediate. The reaction expands the versatility of carbohydrate chemistry by converting an aldose sugar into a ketose sugar.

Industrial relevance centers on the production of high-fructose syrups, where glucose isomerase is used to increase the fructose content of glucose-rich streams. This enzyme is a standard biocatalyst in the sugar industry because it enables efficient, large-scale conversion under conditions compatible with food processing. Commercial preparations are commonly produced by microorganisms, with Bacillus coagulans being a well-known source.

In practice, glucoseisomerase is often employed in immobilized form to allow continuous operation and reuse, which improves process economics. Operating conditions typically involve moderate temperatures and near-neutral to mildly alkaline pH; thermostable variants from certain microbes permit higher-temperature operation, offering faster reaction rates and reduced contamination risk. Cofactors such as Mg2+ or Mn2+ are commonly required for activity, supporting the enzyme’s catalytic mechanism.

Beyond fructose production, glucoseisomerase is used as a biocatalyst in carbohydrate chemistry and related biotechnology applications where selective aldose-to-ketose isomerization is advantageous. Its robustness and adaptability to immobilization have contributed to its enduring role in industrial biocatalysis.

See also: isomerase, high-fructose corn syrup, Bacillus coagulans.