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Dextranase is a type of hydrolase that is responsible for catalyzing the breakdown of high-molecular-weight dextran into low-molecular-weight polysaccharides. This process is called dextranolysis. A select group of bacteria and fungi, including yeasts and likely certain complex eukaryotes, produce dextranase enzymes as extracellular enzymes that are released into the environment. These enzymes join dextran's α-1,6 glycosidic bonds to make glucose, exodextranases, or isomalto-oligosaccharides (endodextranases). Dextranase is an enzyme that has a wide variety of applications, some of which include the sugar business, the production of human plasma replacements, the treatment of dental plaque and its protection, and the creation of human plasma replacements. Because of this, the quantity of studies carried out on worldwide has steadily increased over the course of the past couple of decades. The major focus of this study is on the most current advancements in the production, administration, and properties of microbial dextranases. This will be done throughout the entirety of the review. [ABSTRACT FROM AUTHOR]

• Increase the thermotolerance of enzyme by introducing Disulfide Bridge. • The optimum temperatures of mutants were improved 25 °C–35 °C. • The catalytic efficiency of A978C-A1013C has increased by 2.63 times. • Mutation causes changes in the glycosidic bond of the catalytic product. The disulfide bridge is a very important part of the peptide chain and plays an important role in stabilizing the protein structure and maintaining its active function. One hundred and fourteen potential disulfide bridges were determined by Disulfide by Design™, and 4 disulfide bridges were constructed for the purpose of obtaining new enzyme species with high thermotolerance. High thermotolerance is achieved by increasing the number of hydrogen bonds between amino acids. The optimum temperatures of mutant L838C-V887C and A948C-A1013C were improved by 10 °C compared to that of the original enzyme, which was beneficial to reduce the viscosity of the reaction system. Some of the mutations resulted in the alteration of catalytic specificity, and the products D739C-F932C and A948C-A1013C catalyzed synthesis of dextran containing a new α(1-4) glycosidic linkage and α(1-2) glycosidic linkage. This study may provide information valuable for increasing the reaction temperature of recombinant dextransucrase. The molecular docking study presents a plausible explanation for reaction specificity alteration and optimum temperature improvement for the mutants. [ABSTRACT FROM AUTHOR]

Dextranases are hydrolases that exclusively catalyze the disruption of α−1,6 glycosidic bonds. A series of variant enzymes were obtained by comparing the sequences of dextranases from different sources and introducing sequence substitutions. A correlation was found between the number of amino acids in the 397–401 region and the hydrolytic process. When there were no more than 5 amino acids in the 397–401 region, the enzyme first hydrolyzed the dextran T70 to a low molecular weight dextran with a molecular weight of about 5000, then IMOs 1 1 IMOs: isomaltooligosaccharides. G: glucose, G2: maltose, G3: maltotriose, G4: maltotetraose, G5: maltopentaose, G6: maltohexaose, G7: maltoheptaose, IG2: isomaltose, IG3: isomaltotriose, IG4: isomaltotetraose, IG5: isomaltopentaose appeared in the system if the degradation continued, showing a clear sequential relationship. And when there are more than 5 amino acids in the 397–401 region, IMOs were produced at the beginning of hydrolysis and continue to increase throughout the hydrolytic process. At the same time, we investigated the enzymatic properties of the variants and found that the hydrolytic rate of A-Ca was 11 times higher than that of the original enzyme. The proportion of IMOs produced by A-Ca was 80.68%, which was nearly10% higher than the original enzyme, providing a new enzyme for the industrial preparation of IMOs. • One of the factors affecting the hydrolysis process of Aodex was determined. • Using sequence substitution method for molecular modification. • The hydrolysis rate of variant A-Ca increased by 11 times. • The proportion of IMOs produced by A-Ca was 80.68% which increased by nearly 10% compared to the WT. [ABSTRACT FROM AUTHOR]

Homogeneous low molecular weight dextran can be used to improve microcirculation and expand blood volume. However, the synthesis and separation of low molecular weight dextran are chemically difficult and environmentally unfriendly. Here, a one-step strategy for the synthesis of homogeneous low molecular weight dextran was developed. Dextransucrase and dextranase were fused by the addition of different length linker peptides. An artificial bifunctional enzyme was created to directly convert sucrose into low molecular weight dextran (13,050 Da), and the related substrate channel mechanism was found. The substrate channel adaptability was studied by changing the length of the linker and its corresponding product behavior. Compared with the mixture of two free enzymes, the residence lag time demonstrates the degree of substrate channelization of a series of fusion enzymes. And found that the highest channelization degree is not equal to produce homogenous dextran. Whereas a fusion enzyme with the appropriate linker (the one with the best substrate channel adaptation) will produce dextran with a homogeneous molecular weight. By studying the temperature dynamics of the fusion enzyme to adjust the two-stage catalytic efficiency of the fusion enzyme, we have increased the yield of low molecular weight homogeneous dextran (Yield of 62 %). [Display omitted] • A one-step strategy for the synthesis of homogeneous low molecular weight dextran. • A series of dextransucrase and dextranase fusions were created. • The intramolecular channels of fusion enzymes were proven and the substrate channel adaptability was studied. • Homogenous low molecular weight dextran was obtained by a successful one-step enzymatic process. [ABSTRACT FROM AUTHOR]

Blue algae, a type of harmful microalgae, are responsible for causing harmful algal blooms that result in severe environmental issues. To address this problem, a biopolysaccharide-based flocculant was developed for treating blue algae blooms. This flocculant was created by modifying high molecular weight dextran using the natural cationic monomer betaine (Dex-Bet), making it environmentally friendly. Various techniques were used to characterize the prepared Dex-Bet flocculant, including infrared spectroscopy (FTIR), nuclear magnetic resonance hydrogen spectroscopy (1H NMR), X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The effectiveness of the Dex-Bet flocculant was evaluated using kaolin-simulated wastewater. The results showed that the treated supernatant had a transmittance of up to 98.25 %. Zeta potential analysis revealed that the main mechanisms of flocculation were charge neutralization, charge patching, and adsorption bridging. The application of Dex-Bet in treating blue-green algae resulted in a maximum removal rate of 98.2 %. This study provides a potential flocculant for blue algae bloom treatment. [Display omitted] [ABSTRACT FROM AUTHOR]