Immobilization of dextransucrase on regenerated benzoyl cellulose carriers

Leloir Glycosyltransferases in Applied Biocatalysis: A Multidisciplinary Approach

Enzymes are nature’s catalyst of choice for the highly selective and efficient coupling of carbohydrates. Enzymatic sugar coupling is a competitive technology for industrial glycosylation reactions, since chemical synthetic routes require extensive use of laborious protection group manipulations and often lack regio- and stereoselectivity. The application of Leloir glycosyltransferases has received considerable attention in recent years and offers excellent control over the reactivity and selectivity of glycosylation reactions with unprotected carbohydrates, paving the way for previously inaccessible synthetic routes. The development of nucleotide recycling cascades has allowed for the efficient production and reuse of nucleotide sugar donors in robust one-pot multi-enzyme glycosylation cascades. In this way, large glycans and glycoconjugates with complex stereochemistry can be constructed. With recent advances, LeLoir glycosyltransferases are close to being applied industrially in multi-enzyme, programmable cascade glycosylations.

Immobilization of glucansucrase for the production of gluco-oligosaccharides from Leuconostoc mesenteroides

Glucansucrase from Leuconostoc mesenteroides was immobilized in 1 % (w/v) with sodium alginate to produce oligosaccharides. Glucansucrase gave three activity bands of approx. 240, 178, and 165 kDa after periodic acid-Schiff staining with sucrose. The immobilized enzyme had 40 % activity after ten batch reactions at 30 °C and 75 % activity after a month of storage at 4 °C, which is six times more stable than the free enzyme. Immobilized enzyme was more stable at lower (3.5-4.5) and higher (6.5-7.0) pH ranges and higher temperatures (35-40 °C) compared with the free enzyme. Immobilized and free glucansucrase were employed in the acceptor reaction with maltose and each produced gluco-oligosaccharide ranging from trisaccharides to homologous pentasaccharides.

Chitosanase Immobilization Using Composite Carrier of Sodium Alginate/Cellulose

Sodium alginate and cellulose were combined to use as a composite carrier forPseudomonassp. CUY8 chitosanase immobilization. For free enzyme, immobilized chitosanase within different carriers of sodium alginate and composite carrier, Km values were 1.919, 9.27, and 5.91µM, respectively. The increase of Km value of immobilized chitosanase with composite carrier was lower than that of single carrier. This indicates that the composite carrier of sodium alginate/ cellulose improves the affinity of chitosanase to the substrate. Furthermore, chitosanase immobilization using composite carrier shows improved thermal stability ranging from 65 to 80°C, and enzyme residual activities were more than 75%. The effects of ratio of enzyme to substrate on chitooligosaccharides (COS) production were determined, and COS yields with composite carrier was 68% at optimum ratio of 1:1. Since the immobilization process using composite carrier is simple and effective, this method could be used for the industrial production of COS.

Stability Study of Crude Dextransucrase from Leuconostoc citreum NRRL B-742

In the present work, the stability of crude dextransucrase from Leuconostoc citreum B-742 was evaluated in synthetic and in cashew apple juice culture broth. Optimum stability conditions for dextransucrase from L. citreum B-742 were different from the reported for its parental industrial strain enzyme (L. mesenteroides B-512F). Crude dextransucrase, from L. citreum B-742, produced using cashew apple juice as substrate, presented higher stability than the crude enzyme produced using synthetic culture medium, showing the same behavior previously reported for dextransucrase from L. mesenteroides B-512F. The crude enzyme presented good stability in cashew apple juice for 48 h at 25°C and pH 6.5.