What is Dextranase?
Dextranase is a class of hydrolases that specifically hydrolyze α-1,6 glycosidic bonds in dextran. It belongs to the glycoside hydrolase family, and its core function is to degrade high-molecular-weight dextran into low-molecular-weight oligosaccharides or monosaccharides. Dextranase can convert natural insoluble dextran into a soluble form, thereby improving its utilization rate.
Sources and Classification of Dextranase
Dextranase has a wide range of sources, including microorganisms and animals. Among these, microorganisms are the main source for current industrial production. High-yield strains of Chaetomium gracile screened through mutagenesis and Aspergillus niger can efficiently synthesize dextranase.
Dextranase is classified into two main types: endo-dextranase and exo-dextranase. Endo-type enzymes randomly break glycosidic bonds inside dextran molecules, rapidly fragmenting large polysaccharides and reducing the molecular weight and viscosity of the polymer. Exo-type enzymes sequentially hydrolyze glucose residues from the ends of dextran molecules, gradually releasing small-molecule products, which are mostly glucose or disaccharides.
Mechanism of Action of Dextranase
The action of dextranase is essentially an enzyme-catalyzed hydrolysis reaction. Its active site has a domain that specifically recognizes the α-1,6 glycosidic bond of dextran. When the enzyme binds to the substrate, the amino acid residues in the active site catalyze the cleavage of the glycosidic bond, leading to the depolymerization of the high-molecular-weight dextran chain.
The specific process is as follows: the enzyme molecule recognizes the specific type of glycosidic bond and its surrounding structure in the dextran molecule through the amino acid residues in the active site. The active site forms a specific binding with the dextran substrate, putting the glycosidic bond of the substrate molecule in a conformation that is easily catalyzed. Through acid-base catalysis or covalent catalysis, it attacks the oxygen atom of the glycosidic bond and breaks the bond. After the glycosidic bond is cleaved, small-molecule products such as oligosaccharides or glucose are generated and dissociate from the enzyme's active site. The free enzyme can recombine with new dextran substrates to repeat the catalytic process.
What is the application of Dextranase in food?
In the sugar industry, dextranase can hydrolyze dextran in beet or cane juice, reduce the viscosity of the sugar solution, avoid the interference of dextran on sucrose crystallization during the crystallization process, and improve the production efficiency and yield of sugar making.
In baked foods, adding an appropriate amount of dextranase can improve dough texture, enhance gluten stability, and improve the taste and shelf life of bread.
Dextranase can also be used for juice clarification, removing turbidity formed by dextran in juice and improving juice transparency.