[Transglycosylation of benzo[h]quinazolines].

This was the first study to apply cyclodextrin glucanotransferases (CGTase, EC 2.4.1.19) produced by mesophilic, thermophilic, alkaliphilic, and halophilic bacilli as well as pullulanase, beta-amylase, beta-galactosidase, and beta-fructofuranosidase for transglycosylation of benzo[h]quinazolines. The combination of CGTase produced by Bacillus stearothermophilus ST-88 and gamma-cyclodextrin (CD) used as a donor of glucosyl residues was the most efficient. The derivatives obtained are water-soluble. The synthesized products have been purified by various chromatographic methods and their fine structures have been determined.

[Production of fructooligosaccharide syrup from sucrose in combination with palatinose and trehalose].

The fructofuranosidases (EC 3.2.1.26) of Aspergillus niger St-0018 and A. foetidus St-0194 were used to produce fructooligosaccharides (FOS) under periodic and continuous conditions. The incorporation of cells into calcium alginate gel gave the most efficient immobilized biocatalysts. The feasibility of transforming residual sucrose into palatinose and trehalulose using isomaltulose synthase (EC 5.4.99.11) was demonstrated.

[Transglycosylation of L-ascorbic acid].

Cyclodextrin glucanotransferases (CGTase, EC 2.4.1.19) produced by mesophilic, thermophilic, and halophilic bacilli, as well as maltase (EC 3.2.1.20) produced by various strains of Saccharomyces cerevisiae have been applied for transglycosylation of L-ascorbic acid using starch, maltodextrin, gamma-cyclodextrin, and maltose as donors of glucosyl residue. The CGTases produced by thermophilic strains are the most efficient. The degree of transglucosylation is more than 60%.

[Combined enzymatic modification of stevioside and rebaudioside A].

Cyclodextrin glucanotransferases (CGTases, EC 2.4.1.19) produced by mesophilic, thermophilic, alkaliphilic, and halophilic bacilli were used for transglycosylating stevioside and rebaudiosides A with the use of starch as a donor. CGTases produced by B. stearothermophilus B-5076 B. macerans BIO-4m were the most effective biocatalysts. This method can be successfully used for direct transglycosylation of stevia extract without purification of its individual components.

[Transglycosylation of stevioside by cyclodextrin glucanotransferases of various group of microorganisms]. / Transgliukozilirovanie steviozida tsiklodeksringliukanotransferazami razlichnykh grupp mikroorganizmov.

Cyclodextrin glucanotransferases (CGTases, EC 2.4.1.19), produced by mesophilic, thermophilic, alkaliphilic, and halophilic bacilli, were used for the transglycosylation of stevioside to remove bitterness and aftertaste, with cyclodextrins (CDs) being used as donors. It was shown that CGTases produced by extremophiic microorganisms are effective biocatalysts. Optimal temperature and pH of these enzymes were at pH 6.5-7.5 and 45 degrees C, respectively. The optimal stevioside-to-CD ratio and total concentration of dry matter for the synthesis of best-taste product were 1:1 (w/w) and 11.6%, respectively.

[Characteristics of cyclodextrin production using cyclodextrin glucanotransferases of various groups of microorganisms]. / Osobennosti polucheniia tsiklodekstrinov s pomoshch'iu tsiklodekstringliukanotransferaz razlichnykh grupp mikroorganizmov.

Cyclodextrin glucanotransferases (CGTases; EC 2.4.1.19) from newly isolated mesophilic, thermophilic, alkalophilic, and halophilic bacilli, as well as from thermoactinomycetes, have been purified to homogeneity, and some of their physicochemical and biochemical characteristics (cyclizing, disproportionating, and hydrolytic activities) have been studied. Cyclodextrin (CD) production in the presence and absence of compounds favoring formation of complexes had certain specific features. We were able to demonstrate that CG-Tases of mesophilic and thermophilic strains form mixtures of alpha-, beta-, and gamma-CDs, whereas the enzymes from halophilic and alkalophilic microorganisms preferentially catalyze the formation of beta-CDs.

[New cyclomaltodextrin-glucanotransferases, produced by Bacillus macerans]. / Novye tsiklomal'todekstrin-gliukanotransferazy, produtsiruemye Bacillusmacerans.

For the first time, microorganisms producing cyclomaltodextrin glucan transferases (CGT, EC 2.4.1.19) were isolated from soil samples of various ecogeographical regions. These microorganisms were identified as Bacillus macerans. The enzymes were purified by affinity chromatography on a alpha-cyclodextrin polymer and gel filtration on Biogel P-450 and proved to be electrophoretically homogeneous. Some of their physicochemical and biochemical properties are reported.

[A new method for immobilizing microbial cells by crosslinking]. / Novyi metod immobilizatsii kletok mikroorganizmov poperechnoi sshivkoi.

A method for immobilization of microbial cells was developed designed. The method uses based on generation of reactive aldehyde groups on the cell wall surface under conditions of periodate oxidation. The linking of aldehyde groups by various bifunctional aromatic diamines and then by glutaraldehyde produced immobilized cells, which are promising for the use in biocatalysis with high-molecular-weight substrates of high molecular weight.

[Immobilization of cells by entrapping in aubasidan]. / Immobilizatsiia kletok vkliucheniem v aubazidan.

A new technique of immobilization of microbial cells by entrapping in aubasidan, a microbial polysaccharide, was developed. This technique was applied to three cultures: Erwinia aroidea, Pseudomonas sp., and Alcaligenes faecalis, the producers of aspartase and L-aspartate beta-decarboxylase. The new method is effective. After immobilization, microbial cells retained 79-91% of their initial enzymatic activity.

[Comparative characteristics of cyclodextrin glycosyltransferases from various groups of microorganisms]. / Sravneitel'naia kharakteristika tsiklodekstringlikoziltransferaz razlichnykh grupp mikroorganizmov.

Cyclodextrin glycosyltransferases (CGT-ase, 1.4-alpha-glucanotransferase, cyclizing, EC 2.4.1.19) produced by some thermophilic, alkalophilic and mesophilic bacterial strains, were isolated and characterized. It was shown that thermophilic and mesophilic CGT-ases represent a mixture of alpha-, beta- and gamma-cyclodextrins (CD), alpha-cyclodextrin being the predominant component. Alkalophilic enzymes produce only beta-CD and are able to produce CD not only from starch but also from maltose, melibiose, maltotriose, amylose and amylopectin. The optimal conditions for the catalytic activity of the enzymes were determined. It was found that calcium, magnesium and zinc ions have a beneficial effect on the specific activity of these enzymes. The amino acid composition of the enzymes was studied.