Microbial Dextran-Hydrolyzing Enzymes: Fundamentals and Applications

Abstract

Dextran is a chemically and physically complex polymer, breakdown of which is carried out by a variety of endo- and exodextranases. Enzymes in many groups can be classified as dextranases according to function: such enzymes include dextranhydrolases, glucodextranases, exoisomaltohydrolases, exoisomaltotriohydrases, and branched-dextran exo-1,2-α-glucosidases. Cycloisomalto-oligosaccharide glucanotransferase does not formally belong to the dextranases even though its side reaction produces hydrolyzed dextrans. A new classification system for glycosylhydrolases and glycosyltransferases, which is based on amino acid sequence similarities, divides the dextranases into five families. However, this classification is still incomplete since sequence information is missing for many of the enzymes that have been biochemically characterized as dextranases. Dextran-degrading enzymes have been isolated from a wide range of microorganisms. The major characteristics of these enzymes, the methods for analyzing their activities and biological roles, analysis of primary sequence data, and three-dimensional structures of dextranases have been dealt with in this review. Dextranases are promising for future use in various scientific and biotechnological applications

Cloning, characterization, and heterologous expression of a dextranase gene from Penicillium pinophilum SMCU3-14

“…Although heterologous protein expression in E. coli is mainly transported into the periplasmic space 31 , the potential secretion of recombinant dextranase observed in this study may occur due to the native secretion signal of SMCU-DEX present in the construct being operatively functional in E. coli. Regardless, the activity of dextranase from E. coli was confirmed in both agar diffusion assays and blue dextran-SDS-PAGE zymographs.…”

Biodegradation of Pharmaceutical Wastes in Treated Sewage Effluents by Bacillus subtilis 1556WTNC

“…Two types of enzymes are involved in the substrate degradation, exo-enzymes and endo-enzymes. Exo-enzymes are produced in the microorganism cell, but released outside the cell wall to solubilise insoluble particulates that are attached to the cell walls (Khalikova et al 2005). Once solubilised, these substrates enter the microorganism cells where the degradation takes place by endo-enzymes (Gerardi 2003).…”

Dextranas em açúcares do estado de São Paulo

“…4,5,19 Dados sobre a polidispersividade (razão Mw/Mn) propiciam avaliar a amplitude da distribuição das massas molares de um polimero. 18 Dextranas mais polidispersas apresentam uma maior amplitude na sua distribuição de massa, tendendo assim a apresentar um maior número de ramificações, sendo bem estabelecido que a solubilidade das dextranas em soluções hidroalcoólicas e dependendo da bactéria produtora, mesmo em água, diminui à medida que aumenta o número de ramificações.…”

“…18 Dextranas mais polidispersas apresentam uma maior amplitude na sua distribuição de massa, tendendo assim a apresentar um maior número de ramificações, sendo bem estabelecido que a solubilidade das dextranas em soluções hidroalcoólicas e dependendo da bactéria produtora, mesmo em água, diminui à medida que aumenta o número de ramificações. 5,[18][19][20] As massas molares de polímeros devem ser expressas em termos médios, uma vez que suas curvas de distribuição de massas molares (DPM) são relativamente largas. A massa molar média (Mz) é mais sensível às frações de mais alta massa de um polímero, que a massa molar média ponderal (Mw) e a massa numérica (Mn).…”