What is Hemicellulase?

Hemicellulase is a type of enzyme that degrades the plant cell wall polymer hemicellulose. This polymer helps to cross-link the plant cell wall components to give the walls rigidity. Hemicellulase is used commercially in baking products and in various other food preparation technologies. This type of enzyme is also produced by microorganisms that live in the human digestive tract and degrade dietary hemicellulose, which humans are incapable of digesting. It is taken by some as a supplement to aid in digestion.

Hemicelluloses are polysaccharides — long chains of sugars — that are part of the plant cell wall. They can be very complex molecules and be comprised of a number of different types of sugars. They differ from the plant cell wall structural compound cellulose, which forms a much longer chain and is comprised entirely of glucose molecules. Hemicellulose is a cross-linking agent and interconnects cellulose microfibrils. It can also link the cellulose to other cell wall components.

The complexity of hemicellulose means that there are many different types of hemicellulase. Various types of this enzyme have different applications in biotechnology, particularly in the food sciences. The enzyme is often used in combination with other enzymes that degrade plant cell walls or starches.

A primary use of hemicellulase is in the baking industry. It is used in cake mixes, baked goods, and frozen dough. The enzyme enhances the quality of the dough and helps with storage life.

Fruit juices and alcoholic beverages can be produced using this type of enzyme. In particular, hemicellulases are used in the production of wines. They help remove unwanted compounds from the skins of the grapes that might contaminate the taste of the wine.

Although plants make hemicellulases for growth and development, most of the commercial interest is in the enzymes produced by microorganisms. The enzymes are produced industrially from bacteria and fungi. In some cases, these organisms have been genetically engineered to produce optimal amounts of hemicellulase.

The important role of hemicellulases in many biotechnological applications has led to a great deal of interest in determining their structure and function. The enzymes are often in a modular form; different parts of their structures have varying functions. For this type of enzyme, part is specialized to bind to the hemicellulose, while another part breaks down the bond connecting the sugars by a process known as hydrolysis. This involves adding a molecule of water to the bond, which causes it to break open.

Microorganisms that produce hemicellulases are also found in the digestive tract of humans and higher animals. Since humans cannot degrade hemicellulose, it is considered fiber. The microorganisms in the human body break down some of the hemicellulose, helping it to be digested. Supplements of hemicellulase are available, but as with any supplement, one should consult with a doctor before consuming them.