Enzymatic Synthesis of Dextran

Koepsell, H. J.; Tsuchiya, H. M.

doi:10.1128/jb.63.2.293-295.1952

Cited by 84 publications

(26 citation statements)

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“…The acceptor reaction was first described by Koepsell et al [2]. In the presence of sucrose, they have observed that introduction into the reaction medium of molecules, like maltose, isomaltose, and O ‐α‐methylglucoside, shifted the pathway of glucan synthesis towards the production of oligosaccharides.…”

Section: Mechanism Of Glucansucrase Actionmentioning

confidence: 99%

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Glucansucrases: mechanism of action and structure–function relationships

1999

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Glucansucrases are produced principally by Leuconostoc mesenteroides and oral Streptococcus species, but also by the lactic acid bacteria (Lactococci, Lactobacilli). They catalyse the synthesis of high molecular weight D-glucose polymers, named glucans, from sucrose. In the presence of efficient acceptors, they catalyse the synthesis of low molecular weight oligosaccharides. Glucosidic bond synthesis occurs without the mediation of nucleotide activated sugars and cofactors are not necessary. Glucansucrases have an industrial value because of the production of dextrans and oligosaccharides and a biological importance by their key role in the cariogenic process. They were identified more than 50 years ago. The first glucansucrase encoding gene was cloned more than 10 years ago. But the mechanism of their action remains incompletely understood. However, in order to synthesise oligosaccharides of biological interest or to develop vaccines against dental caries, elucidation of the factors determining the regiospecificity and the regioselectivity of glucansucrases is necessary. The cloning of glucansucrase encoding genes in addition to structure-function relationship studies have allowed the identification of important amino acid residues and have shown that glucansucrases are composed of two functional domains: a core region (ca. 1000 amino acids) involved in sucrose binding and splitting and a C-terminal domain (ca. 500 amino acids) composed of a series of tandem repeats involved in glucan binding. Enzymology studies have enabled different models for their action mechanism to be proposed. The use of secondary structure prediction has led to a clearer knowledge of structure-function relationships of glucansucrases. However, mainly due to the large size of these enzymes, data on the three-dimensional structure of glucansucrases (given by crystallography and modelling) remain necessary to clearly identify those features which determine function.

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Section: Mechanism Of Glucansucrase Actionmentioning

confidence: 99%

“…They catalyse the synthesis of high molecular weight d ‐glucose polymers named glucans from sucrose. When efficient acceptors, like maltose or isomaltose, are added to the reaction medium, glucansucrase catalyses the synthesis of low molecular weight oligosaccharides instead of high molecular weight glucan [2].…”

Section: Introductionmentioning

confidence: 99%

Glucansucrases: mechanism of action and structure–function relationships

1999

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“…This is the case, for example, with the enzyme from L. mesenteroides NRRL B-512F which is used to produce the dextran polymers of industrial interest (chromatography supports, photographic emulsions, iron carriers, blood plasma substitutes). If efficient acceptors are added to the reaction mixture, dextran sucrase catalyzes the synthesis of low molecular weight oligosaccharides instead of high molecular weight polymers [21][22][23]. Maltose and isomaltose are the most efficient acceptors in this reaction.…”

Section: Fructosyl-transferase the Japanese Company Meijimentioning

confidence: 99%

Enzymatic synthesis of oligosaccharides

Monsan¹

1995

FEMS Microbiology Reviews

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The biological interest of oligosaccharides is growing very rapidly, and necessitates the development of efficient synthesis reactions. The stereo-and regio-selectivity of enzyme catalysis is a key advantage in this field, as a complementary tool to the chemical approach. Two types of enzymes can be applied to the obtention of oligosaccharides: Hydrolytic enzymes, which can catalyze either reverse hydrolysis (thermodynamic control) or transglycosylation (kinetic control) synthesis reactions; and transferase enzymes, which can use simple carbohydrates from agricultural origin as glycosyl donors.

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“…The disadvantages of conventional dextran production are the time and energy required to propagate cells, and the synthesis of dextran under constantly changing fermentation conditio-" resulting in less than optimal dextral production, xr~ the 1950s the use of a cell-free enzyme solution permitted dextran synthesis under controlled conditions yielding a polymer of greater purity. Koepsrell and Tsuchiya [10] first established the conditions for production of dextransucrase and these were further described by Jeanes [11]. It is possible to obtain eight times more dextansuerase activity with the improved system.…”

Section: Productionmentioning

confidence: 99%

Exocellular polysaccharides produced by lactic acid bacteria

Cerning¹

1990

FEMS Microbiology Letters

429

233

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The production of homopolysaccharides (dextrans, mutans) and heteropolysaccharides by lactic acid bacteria, their chemical composition, their structure and their synthesis are outlined. Mutans streptococci, which include Streptococcus mutans and S. sobrinus produce soluble and insoluble α‐glucans. The latter may contain as much as 90%α‐1–3 linkages and possess a marked ability to promote adherence to the smooth tooth surface causing dental plaque. Dextrans produced by Leuconostoc mesenteroides are high molecular weight α‐glucans having 1–6, 1–4 and 1–3 linkages, varying from slightly to highly branched; 1–6 linkages are predominant. Emphasis is put on exopolysaccharide producing thermophilic and mesophilic lactic acid bacteria, which are important in the dairy industry. The produced polymers play a key role in the rheological behaviour and the texture of fermented milks. One of the main problems in this field is the transitory nature of the thickening trait. This instability is not yet completely understood. Controversial results exist on the sugar composition of the slime produced, but galactose and glucose have always been identified with galactose predominating in most cases.

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Enzymatic Synthesis of Dextran

Cited by 84 publications

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Glucansucrases: mechanism of action and structure–function relationships

Glucansucrases: mechanism of action and structure–function relationships

Enzymatic synthesis of oligosaccharides

Exocellular polysaccharides produced by lactic acid bacteria

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