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Cellulase, a lytic enzyme to break plant cell walls for protein extraction

Posted by The Protein Man on May 9, 2017 2:23:34 PM
The Protein Man

Plant.jpgLytic enzymes such as cellulase, lysozome, labiase, achropeptidase and a number of others, play a significant role in protein and DNA extraction. While different lytic enzymes can be used for different applications, cellulase is usually the enzyme of choice when it comes to breaking down plant cell walls. What is it about cellulase that makes it particularly useful for plant cell lysis? Here are some things you should know.

Understanding Cellulases: Getting Down to the Basics

Cellulase is an enzyme produced by fungi, bacteria and/or protozoans that help decompose cellulose and other related polysaccharides (e.g. hemicellulose, lichenin, and cereal beta-D-glucans) into monosaccharides or simple sugars (i.e. beta-glucose), shorter polysaccharides and/or oligosaccharide by hydrolyzing the 1,4-beta-D-glycosidic linkages.  

This lytic enzyme is economically significant since it makes the majority of plant components available for further processing, a nearly impossible feat since cellulose molecules bind strongly to each other and are rather difficult to break down. Considering the fact that cellulose is our most abundant renewable biological resource and is one of the cheapest energy sources we have on the planet, harnessing its full potentials can have a significant impact, not only in the economy but our environment and energy security as well.

Types of Cellulases

Based on the type of reaction they catalyze, cellulases can be categorized as endocellulases, exocellulases (cellobiohydrolases) and beta-glucosidases.

  • Endocellulase (CMCase) – generate new chain ends by randomly cleaving internal bonds at amorphous sites. Upon acting on the cellulose chains, endocellulases produce glucose, cellodextrins and/or insoluble cellulose fragments. However, cellobiose or longer cellodextrins are produced if the endocellulase acted “processively”.   
  • Exocellulase – produces tetrasaccharides and/or disaccharides by cleaving two to four units from the reducing or nonreducing ends of the exposed chains which were produced by the action of endocellulases.
  • Beta-glucosidase – hydrolyzes the resulting exocellulase products into individual monosaccharides.

How Are Cellulases Used?

Cellulases are used in many different applications across a wide range of industries. Some of its more popular applications include the following:

  • Commercial food processing – Cellulases play a significant role in the wine making and brewing industries, and in the extraction of olive oil and carotenoids.
  • Agriculture – Cellulases are used for plant pathogen and disease control, enhanced seed germination, plant growth and flowering, improved soil quality, etc.
  • Feed production – Production of energy-rich animal feeds is made possible with the use of cellulases.
  • Textile industry – Cellulase helps improve fabric quality and restore the color and brightness of textile materials.
  • Laundry industry - Improved cleaning action and enhanced fabric color are achieved with the use of cellulases. It also protects cloth fibers.
  • Pulp and paper industry – Cellulases are used to improve paper quality while reducing energy and chlorine requirement. It is also used to achieve improved deinking performance.
  • Biofuel production - Cellulases effectively convert lignocellulosic materials such as sugarcane bagasse, corncob, rice straw, saw dust, and forest residues to ethanol.

Breaking Down the Cell Walls Using Cellulase

While traditional methods of cell lysis use physical methods to disrupt and force open the cells, researchers now prefer using enzymes for a number of reasons, which include the following:

  • If not performed properly, some physical or mechanical methods may lead to sample denaturation and aggregation.
  • Coming up with reproducible results can be a challenge, especially when using homogenization and grinding methods, due to the inaccurate terminology used in defining the handling of the sample.
  • Physical and mechanical methods require more effort and may necessitate the use of expensive equipment (e.g. French press, sonicator, etc.).

In contrast, the use of lytic enzymes such as cellulase produces reproducible results, is ideal for different applications and is more suitable for modern laboratory processes.

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Topics: Protein Extraction

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