Glucose isomerase (GI, EC 5.3.1.5; also known
as D-xylose ketol isomerase, xylose isomerase (XI), xylose ketoisomerase, and
xylose ketol-isomerase), is one of the three most commonly produced industrial
enzymes, along with amylase and protease. This enzyme is extensively used in
the industrial production of high-fructose corn syrup (HFCS), and it can also
be used to boost cellulosic ethanol yield and used in the production of low
glycemic index foods.