The enzymic production of levan

Hestrin, S.; Avineri-Shapiro, S.; Aschner, M.

doi:10.1042/bj0370450

Cited by 108 publications

(29 citation statements)

References 9 publications

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“…The product causing the jellification was named dextran due to its positive rotatory power. The corresponding extracellular enzyme was named dextransucrase (73). A common feature of all dextrans is the abundance of ␣-(136) linkages with some branching points at position 2, 3, or 4.…”

Section: Reactions Catalyzed and Glucan Product Synthesismentioning

confidence: 99%

Structure-Function Relationships of Glucansucrase and Fructansucrase Enzymes from Lactic Acid Bacteria

Hijum

Kralj

Ozimek

et al. 2006

Microbiol Mol Biol Rev

393

315

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SUMMARY Lactic acid bacteria (LAB) employ sucrase-type enzymes to convert sucrose into homopolysaccharides consisting of either glucosyl units (glucans) or fructosyl units (fructans). The enzymes involved are labeled glucansucrases (GS) and fructansucrases (FS), respectively. The available molecular, biochemical, and structural information on sucrase genes and enzymes from various LAB and their fructan and α-glucan products is reviewed. The GS and FS enzymes are both glycoside hydrolase enzymes that act on the same substrate (sucrose) and catalyze (retaining) transglycosylation reactions that result in polysaccharide formation, but they possess completely different protein structures. GS enzymes (family GH70) are large multidomain proteins that occur exclusively in LAB. Their catalytic domain displays clear secondary-structure similarity with α-amylase enzymes (family GH13), with a predicted permuted (β/α)8 barrel structure for which detailed structural and mechanistic information is available. Emphasis now is on identification of residues and regions important for GS enzyme activity and product specificity (synthesis of α-glucans differing in glycosidic linkage type, degree and type of branching, glucan molecular mass, and solubility). FS enzymes (family GH68) occur in both gram-negative and gram-positive bacteria and synthesize β-fructan polymers with either β-(2→6) (inulin) or β-(2→1) (levan) glycosidic bonds. Recently, the first high-resolution three-dimensional structures have become available for FS (levansucrase) proteins, revealing a rare five-bladed β-propeller structure with a deep, negatively charged central pocket. Although these structures have provided detailed mechanistic insights, the structural features in FS enzymes dictating the synthesis of either β-(2→6) or β-(2→1) linkages, degree and type of branching, and fructan molecular mass remain to be identified.

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Section: Reactions Catalyzed and Glucan Product Synthesismentioning

confidence: 99%

Structure-Function Relationships of Glucansucrase and Fructansucrase Enzymes from Lactic Acid Bacteria

Hijum

Kralj

Ozimek

et al. 2006

Microbiol Mol Biol Rev

393

315

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“…Levan is a polymer consisting of ␤-2,6-linked fructose residues and found in monocotyledons as a reserve carbohydrate or synthesized by microbial levansucrase (EC 2.4.1.10) from sucrose (3,4). In contrast to a plant levan, a microbial levan generally has a lot of branching points at the C-1 position, except for a levan from Serratia levanicum (4,5).…”

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confidence: 99%

Purification and Characterization of 2,6-β- d -Fructan 6-Levanbiohydrolase from Streptomyces exfoliatus F3-2

Saito¹,

Kondo²,

Kojima

et al. 2000

Appl Environ Microbiol

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Streptomyces exfoliatus F3-2 produced an extracellular enzyme that converted levan, a ␤-2,6-linked fructan, into levanbiose. The enzyme was purified 50-fold from culture supernatant to give a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weights of this enzyme were 54,000 by SDS-PAGE and 60,000 by gel filtration, suggesting the monomeric structure of the enzyme. The isoelectric point of the enzyme was determined to be 4.7. The optimal pH and temperature of the enzyme for levan degradation were pH 5.5 and 60°C, respectively. The enzyme was stable in the pH range 3.5 to 8.0 and also up to 50°C. The enzyme gave levanbiose as a major degradation product from levan in an exo-acting manner. It was also found that this enzyme catalyzed hydrolysis of such fructooligosaccharides as 1-kestose, nystose, and 1-fructosylnystose by liberating fructose. Thus, this enzyme appeared to hydrolyze not only ␤-2,6-linkage of levan, but also ␤-2,1-linkage of fructooligosaccharides. From these data, the enzyme from S. exfoliatus F3-2 was identified as a novel 2,6-␤-D-fructan 6-levanbiohydrolase (EC 3.2.1.64).It has been reported that oligosaccharides appear to exhibit various physiological functions according to their structures. As the functions of the oligosaccharides are recognized, the production methods become important. An attempt to synthesize a large number of novel oligosaccharides has been made by using sugar hydrolases or sugar transferases. We have been studying the effective production of novel oligosaccharides (11,(13)(14)(15)(19)(20)(21)(22) from such unused natural fructans as levan and inulin by the microbial polysaccharide-degrading enzymes. Also we confirmed that two of these oligosaccharides, di-Dfructose-1,2Ј:2,3Ј-dianhydride (DFA III) (17) and di-D-fructose-2,6Ј:6,2Ј-dianhydride (DFA IV) (12), had effects on increasing calcium absorption in the small intestine of rats, which could be expected to have practical applications in such fields as treatment with functional food or medicine to prevent osteoporosis.In the course of these studies, Streptomyces exfoliatus F3-2 was isolated as a strain producing a levan-degrading enzyme (LDE) that effectively produces levanbiose from levan (21). Levan is a polymer consisting of ␤-2,6-linked fructose residues and found in monocotyledons as a reserve carbohydrate or synthesized by microbial levansucrase (EC 2.4.1.10) from sucrose (3, 4). In contrast to a plant levan, a microbial levan generally has a lot of branching points at the C-1 position, except for a levan from Serratia levanicum (4, 5). In our previous study (21), we demonstrated that the combination of the LDE from S. exfoliatus F3-2 and levan from S. levanicum was quite efficient for the large-scale preparation of levanbiose, with a maximum production yield of levanbiose of 84% (wt/wt) from 50 mg of levan per ml. The linear nature of the levan molecule from S. levanicum seems to contribute to this high yield.To date, three types of microbial LDEs have been reported:...

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“…Hestrin et al (14) named the enzyme responsible for dextran production by Leuconostoc mesenteroides dextransucrase and Van Hijum et al (33) purified a levansucrase-synthesizing EPS of the levan type from L. reuteri. It was the aim of this work to study the metabolism of sucrose as well as the effect of substrate concentration on sucrose metabolism, EPS production, and the biochemical na-ture of the respective end products formed by L. sanfranciscensis.…”

mentioning

confidence: 99%

Exopolysaccharide and Kestose Production by Lactobacillus sanfranciscensis LTH2590

Korakli

Pavlovic

Gänzle

et al. 2003

Appl Environ Microbiol

118

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The effect was investigated of sucrose concentration on sucrose metabolism and on the formation of exopolysaccharide (EPS) by Lactobacillus sanfranciscensis LTH2590 in pH-controlled fermentations with sucrose concentrations ranging from 20 to 160 g liter ؊1 . The EPS production increased and the relative sucrose hydrolysis activity decreased by increasing the sucrose concentration in the medium. The carbon recovery decreased from 95% at a sucrose concentration of 30 g liter ؊1 to 58% at a sucrose concentration of 160 g liter ؊1 because of the production of an unknown metabolite by L. sanfranciscensis. This metabolite was characterized as a fructo-oligosaccharide. The oligosaccharide produced by L. sanfranciscensis was purified and characterized as a trisaccharide with a glucose/fructose ratio of 1:2. The comparison of the retention time of this oligosaccharide and that of pure oligosaccharide standards using two different chromatography methods revealed that the oligosaccharide produced by L. sanfranciscensis LTH2590 is 1-kestose. Kestose production increased concomitantly with the initial sucrose concentration in the medium.Polysaccharides of plant origin have being used for a long time in the food industry as biothickeners, texture stabilizers, or gelling agents. In the last decades several microbial exopolysaccharides (EPS) have been described as alternatives for plant polysaccharides. Microbial polysaccharides have rheological properties that match the industrial demands and can be produced in large amounts and at high purities. The interest of the food industry in developing multifunctional additives that not only provide the desired improvement of the texture but also have additional nutritional properties led to extensive search for polysaccharides with prebiotic attributes. Prebiotics are nondigestible food ingredients that affect the host beneficially by selectively stimulating the growth and/or activity of specific bacteria in the colon and thus improve host health (12). Fructo-oligosaccharides (FOS), xylo-oligosaccharide, and inulin are some of the prebiotics available for human consumption (5, 24). FOS with prebiotic properties (e.g., kestose and nystose) are polymers of D-fructose joined by ␤(231) linkages and terminated with a D-glucose molecule linked to fructose by an ␣(132) bond as in sucrose (22). The degree of polymerization can vary from 2 to 35. FOS with a degree of polymerization of 3 to 5 are called neosugars (30) and can be enzymatically synthesized from sucrose by using fructosyltransferase from Aspergillus niger (16,17). Mckellar and Modler (23) showed that the maximum activity of ␤-fructosidase, responsible for the hydrolysis of inulin-type polysaccharides by bifidobacteria, was observed with neosugars.Lactic acid bacteria (LAB) are widely used for the production of numerous fermented foods and are generally recognized as safe. Several EPS-producing LAB such as Lactobacillus delbrueckii subsp. bulgaricus, Lactococcus lactis, and Streptococcus thermophilus have been isolated from ferme...

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The enzymic production of levan

Cited by 108 publications

References 9 publications

Structure-Function Relationships of Glucansucrase and Fructansucrase Enzymes from Lactic Acid Bacteria

Structure-Function Relationships of Glucansucrase and Fructansucrase Enzymes from Lactic Acid Bacteria

Purification and Characterization of 2,6-β- d -Fructan 6-Levanbiohydrolase from Streptomyces exfoliatus F3-2

Exopolysaccharide and Kestose Production by Lactobacillus sanfranciscensis LTH2590

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