Basic Information and Classification of Cellulase
Cellulase is a type of enzyme that plays a biocatalytic role in the decomposition of cellulose. It is a protein that can break down cellulose into oligosaccharides or monosaccharides.
Cellulose enzymes are widely present in organisms in nature. Bacteria, fungi, and animals can all produce Cellulase. The Cellulases commonly used in production come from fungi, with typical genera including Trichoderma, Aspergillus, and Penicillium
The strains that produce Cellulase are prone to degradation, leading to a decrease in enzyme production capacity.
The production of Cellulase by bacteria is relatively low, mainly consisting of beta glucan endonucleases, most of which have no degradation activity on crystalline cellulose. The enzymes produced are mostly intracellular or adsorbed on the cell wall, and are not secreted into the culture medium, which increases the difficulty of extraction and purification. Therefore, there is relatively little research on bacteria. However, Cellulases produced by bacteria generally have an optimal pH range of neutral to slightly alkaline. In the past 20 years, with the successful application of neutral Cellulases and alkaline Cellulases in cotton fabric washing and finishing processes and detergent industry, bacterial Cellulase preparations have shown good application prospects.
Cellulose enzymes are widely used in both the food and environmental industries. The addition of Cellulases
Due to the difficulty in purifying Cellulases, they generally contain hemicellulases and other related enzymes such as amylase, protease, etc. in practical applications.
There are various types of Cellulases with a wide range of sources. The structure and function of Cellulases from different sources vary greatly. Due to the high production and high activity of fungal Cellulases, the Cellulases mainly used in animal husbandry and feed industry are fungal Cellulases.
Classification
By composition and function
Cellulases can be divided into endo-1,4- β - D-glucan hydrolase or endo-1,4- β - D-glucanase (EC 3.2.1.4), EG from fungi, Cen from bacteria, exo-1,4- β - D-glucanase (EC 3.2.2.1.91), CBH from fungi, Cex from bacteria, and BG based on their catalytic reaction functions. Endo-1,4-glucanase randomly cleaves the amorphous regions inside cellulose polysaccharide chains. Generate oligosaccharides of different lengths and new chain ends. Exoglucanase acts on the ends of these reducing and non-reducing cellulose polysaccharide chains, releasing glucose or cellobiose. β - glucosidase hydrolyzes cellulose disaccharides to produce two molecules of glucose. Fungal Cellulases have high production and activity, and are mainly used in animal husbandry and feed production from fungal sources.
By the degradation mechanism
The main difference between Cellulase reaction and general enzyme reaction is that Cellulase is a multi-component enzyme system and the substrate structure is extremely complex. Due to the insolubility of the substrate, the adsorption of Cellulase replaces the process of forming ES complexes between the enzyme and the substrate. Cellulase first specifically adsorbs onto the substrate cellulose, and then decomposes cellulose into glucose through the synergistic action of several components.
In 1950, Reese et al. proposed the C1 Cx hypothesis, which suggests that different enzymes must work together to thoroughly hydrolyze cellulose into glucose. The synergistic effect is generally believed to be that the C1 enzyme first attacks the amorphous region of cellulose, forming a new free end required for Cx, and then the CX enzyme cleaves the fibrous disaccharide unit from the reducing or non reducing end of the polysaccharide chain. Finally, the β - glucosidase hydrolyzes the fibrous disaccharide into two glucose units. However, the synergistic order of Cellulase is not absolute, and subsequent studies have found that C1 Cx and β - glucosidase must coexist to hydrolyze natural cellulose. If C1 enzyme is used to crystallize cellulose first, then C1 enzyme is removed, and Cx enzyme is added, this sequence of action cannot hydrolyze crystalline cellulose.
