Gluco - Isomerase

Isomerase enzymes are those enzymes which convert a molecule into its other form, known as isomers (same molecular formula but different structure). These enzymes facilitate the structural rearrangement of the molecules. 

For example:
Glucose ==================> Fructose

L-alanine ==================> D-alanine

Glucose isomerase enzyme is also known by the name of - D-xylose isomerase, D-xylose ketoisomerase, D-xylose ketol isomerase.

Glucose isomerase (GI) enzyme catalyzes the reversible reaction of glucose to fructose and xylose to xylulose, and vice versa. Glucose isomerase enzyme is one of the most important enzymes in the food industry as it has a very significant role in the production of high-fructose corn syrup (HFCS). Glucose isomerase is a cofactor independent enzyme which makes it less expensive and vital among sugar industries. 

Function properties of GI enzyme:

  • pH: 7.0 - 9.0

  • Temperature: 65-80°C

  • Substrate: D-glucose and D-xylose

Some main industrial use of GI enzyme are:

High Fructose Corn Syrup (HFCS) Production:

      High fructose corn syrup is 1.3 times sweeter than sucrose and 1.7 times sweeter than glucose, and very        cost effective because of which it is widely used in products like beverages, bakery products, soft drinks,        dairy products, etc. It is also used as diabetic sweetener.

   HFCS is produced in three steps:

  1. Liquefaction of starch by amylase enzyme,

  2. Saccharification of starch by amyloglucosidase enzyme,

  3. Isomerization of glucose into fructose.

high fructose corn syrup.jpg

Biofuel/Ethanol Production:


As pollution has already crossed it’s threshold, the world is in search of new and eco-friendly fuel and ethanol is the most promising biofuel in today’s time which increases its commercial value. 

Glucose isomerase catalyses the isomerization of xylose to xylulose which is fermented by yeast to produce ethanol. 

Xylitol Production:


Xylitol is one of major sugar-free sweetener agents which finds many applications in food, healthcare and pharmaceutical industries. During the xylitol production, a mixture of xylitol, sorbitol, and arabinitol is produced from which xylitol is purified by the use of glucose isomerase (GI) enzyme as glucose isomerase specifically binds to xylitol.

Xylitol is presently used as a sweetener in food products like soft drinks, candies, toothpaste, chewing gum, mouthwash, etc.

xylitol production.jpg