Cloning and expression of levansucrase from Leuconostoc mesenteroides B-512 FMC in Escherichia coli

Leuconostoc mesenteroides B-512 FMC produces dextran and levan using sucrose. Because of the industrial importance of dextrans and oligosaccharides synthesized by dextransucrase (one of glycansucrases from L. mesenteroides), much is known about the dextransucrase, including expression and regulation of gene. However, no detailed report about levansucrase, another industrially important glycansucrase from L. mesenteroides, and its gene was available. In this paper, we report the first-time isolation and molecular characterization of a L. mesenteroides levansucrase gene (m1ft). The gene m1ft is composed of 1272-bp nucleotides and codes for a protein of 424 amino acid residues with calculated molecular mass of 47.1 kDa. The purified protein was estimated to be about 51.7 kDa including a His-tag based on SDS-PAGE. It showed an activity band at 103 kDa on a non-denaturing SDS-PAGE, indicating a dimeric form of the active M1FT. M1FT levan structure was confirmed by NMR and dot blot analysis with an anti-levan-antibody. M1FT converted 150 mM sucrose to levan (18%), 1-kestose (17%), nystose (11%) and 1,1,1-kestopentaose (7%) with the liberation of glucose. The M1FT enzyme produced erlose [O-alpha-D-glucopyranosyl-(1-->4)-O-alpha-D-glucopyranosyl-(1-->2)-beta-D-fructofuranoside] as an acceptor product with maltose. The optimum temperature and pH of this enzyme for levan formation were 30 degrees C and pH 6.2, respectively. M1FT levansucrase activity was completely abolished by 1 mM Hg2+ or Ag2+. The Km and Vmax values for levansucrase were calculated to be 26.6 mM and 126.6 micromol min-1 mg-1.     

Activation and inhibition of dextransucrase by calcium

Initial rate kinetics of dextran synthesis by dextransucrase (sucrose:1,6-alpha-D-glucan-6-alpha-D-glucosyltransferase, EC 2.4.1.5) from Leuconostoc mesenteroides NRRL B-512F showed that below 1 mM, Ca2+ activated the enzyme by increasing Vmax and decreasing the Km for sucrose. Above 1 mM, Ca2+ was a weak competitive inhibitor (Ki = 59 mM). Although it was an activator at low concentration, Ca2+ was not required for dextran synthesis, either of main chain or branch linkages. Neither was it required for sucrose hydrolysis, acceptor reactions, or enzyme renaturation after SDS-polyacrylamide gel electrophoresis. A model for dextran synthesis is proposed in which dextransucrase has two Ca2+ sites, one activating and one inhibitory. Ca2+ at the inhibitory site prevents the binding of sucrose.     

Gene encoding a dextransucrase-like protein in Leuconostoc mesenteroides NRRL B-512F

A gene, dsrT, encoding a dextransucrase-like protein was isolated from the genomic DNA libraries of Leuconostoc mesenteroides NRRL B-512F dextransucrase-like gene. The gene was similar to the intact open reading frames of the dextransucrase gene dsrS of L. mesenteroides NRRL B-512F, dextransucrase genes of strain NRRL B-1299 and streptococcal glucosyltransferase genes, but was truncated after the catalytic domain, apparently by the deletion of five nucleotides. dsrT mRNA was produced in this strain L. mesenteroides when cells were grown in a sucrose medum, but at a level of 20% of that of dsrS mRNA. The molecular weight of the dsrT gene product was 150,000 by SDS-PAGE. The product did not synthesize dextran, but had weak sucrose cleaving activity. The insertion of five nucleotides at the putative deletion point in dsrT resulted in an enzyme with a molecular weight of 210,000 and with dextransucrase activity.     

Synthesis of 4,6-dideoxysucrose, and inhibition studies of Leuconostoc and Streptococcus D-glucansucrases with deoxy and chloro derivatives of sucrose modified at carbon atoms 3, 4, and 6

Starting from sucrose, 2,3,1',3',4',6'-hexa-O-benzoyl-6-deoxy-6-iodosucrose (1) was synthesized. Reaction of 1 with sulfuryl chloride in pyridine gave 2,3,1',3',4',6'-hexa-O-benzoyl-4-chloro-4,6-dideoxy-6-iodogalactosucr ose (2). Compound 2 was treated with tributyltin hydride in toluene in the presence of a radical initiator, alpha, alpha-azobis(isobutanonitrile) (AIBN), to remove iodine and chlorine groups and give hexa-O-benzoyl-4,6-dideoxysucrose. Benzoyl groups were removed by sodium methoxide in methanol to give 4,6-dideoxysucrose. Sucrose was modified at carbon atom 3, carbon atom 4, or carbon atoms 4 and 6, and these analogs were tested as inhibitors of the D-glucansucrases (D-glucosyltransferases) of Streptococcus mutans 6715 and Leuconostoc mesenteroides B-512F. Sucrose analogs used in this study are 4-deoxysucrose and 4-chloro-4-deoxygalactosucrose with S. mutans 6715 D-glucansucrases (GTF-S and GTF-I), and 3-deoxysucrose, 4-deoxysucrose, 4-chloro-4-deoxygalactosucrose, 6-deoxysucrose, and 4,6-dideoxysucrose with L. mesenteroides B-512F D-glucansucrase. The data indicate that 3-deoxysucrose, 4-deoxysucrose, and 4-chloro-4-deoxygalactosucrose are weak noncompetitive inhibitors for B-512F dextransucrase, with Ki values of 530, 201, and 202mM respectively. For the same enzyme, 6-deoxysucrose was a strong competitive inhibitor, with Ki of 1.60mM, and 4,6-dideoxysucrose was a good competitive inhibitor, with Ki of 20.3mM. 4-Deoxysucrose was a weak noncompetitive inhibitor for both GTF-I and GTF-S, with Ki values of 672 and 608mM, respectively. 4-Chloro-4-deoxygalactosucrose was also a weak noncompetitive inhibitor for GTF-I and GTF-S with Ki values of 391 and 308mM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dextransucrase secretion in Leuconostoc mesenteroides depends on the presence of a transmembrane proton gradient.

The relationship between proton motive force and the secretion of dextransucrase in Leuconostoc mesenteroides was investigated. L. mesenteroides was able to maintain a constant proton motive force of -130 mV when grown in batch fermentors at pH values 5.8 to 7.0. The contribution of the membrane potential and the transmembrane pH gradient varied depending on the pH of the growth medium. The differential rate of dextransucrase secretion was relatively constant at 1,040 delta mU/delta mg (dry weight) when cells were grown at pH 6.0 to 6.7. Over this pH range, the internal pH was alkaline with respect to the external pH. When cells were grown at alkaline pH values, dextransucrase secretion was severely inhibited. This inhibition was accompanied by an inversion of the pH gradient as the internal pH became more acidic than the external pH. Addition of nigericin to cells at alkaline pH partially dissipated the inverted pH gradient and produced a fourfold stimulation of dextransucrase secretion. Treatment of cells with the lipophilic cation methyltriphenylphosphonium had no effect on the rate of dextransucrase secretion at pH 5.5 but inhibited secretion by 95% at pH 7.0. The reduced rate of secretion correlated with the dissipation of the proton motive force by this compound. Values of proton motive force greater than -90 mV were required for maximal rates of dextransucrase secretion. The results of this study indicate that dextransucrase secretion in L. mesenteroides is dependent on the presence of a proton gradient across the cytoplasmic membrane that is directed into the cell.     

Leuconostoc mesenteroides glucansucrase synthesis of flavonoid glucosides by acceptor reactions in aqueous-organic solvents

The enzymatic glucosylation of luteolin was attempted using two glucansucrases: the dextransucrase from Leuconostoc mesenteroides NRRL B-512F and the alternansucrase from L. mesenteroides NRRL B-23192. Reactions were carried out in aqueous-organic solvents to improve luteolin solubility. A molar conversion of 44% was achieved after 24h of reaction catalysed by dextransucrase from L. mesenteroides NRRL B-512F in a mixture of acetate buffer (70%)/bis(2-methoxyethyl) ether (30%). Two products were characterised by nuclear magnetic resonance (NMR) spectroscopy: luteolin-3'-O-alpha-d-glucopyranoside and luteolin-4'-O-alpha-d-glucopyranoside. In the presence of alternansucrase from L. mesenteroides NRRL B-23192, three additional products were obtained with a luteolin conversion of 8%. Both enzymes were also able to glucosylate quercetin and myricetin with conversion of 4% and 49%, respectively.     

Proteolytic processing of dextransucrase of Leuconostoc mesenteroides

Various dextransucrase molecular mass forms found in enzyme preparations may sometimes be products of proteolytic activity. Extracellular protease in Leuconostoc mesenteroides strains NRRL B-512F and B-512FMC dextransucrase preparations was identified. Protease had a molecular mass of 30 kDa and was the predominant form derived from a high molecular mass precursor. The production and activity of protease in culture medium was strongly dependent on pH. When L. mesenteroides dextransucrase (173 kDa) was hydrolyzed by protease, at pH 7 and 37 degrees C, various dextransucrase forms with molecular masses as low as 120 kDa conserving dextransucrase activity were obtained.     

Quasi-irreversible inhibition of enolase of Streptococcus mutans by flouride

Abstract Fluoride at concentrations greater than 0.01 mM was found to be a quasi-irreversible inhibitor of enolase of permeabilized cells of Streptococcus mutans GS-5 and also of isolated yeast enolase. The inhibition appeared to be of the type that has been described for P-ATPases, but was not dependent on added Al³⁺ or Be²⁺ ions. Fluoride inhibition of enolase was not reversed by repeatedly washing the permeabilized cells in chilled fluoride-free medium but could be reversed by the product, phosphoenolpyruvate, or by very high levels of the substrate, 2-phosphoglycerate. Irreversible inhibition of glycolysis was not evident after fluoride treatment of intact cells, washing to remove unbound or loosely bound fluoride and addition of glucose, presumably because intracellular levels of phosphoenolpyruvate were sufficiently high to preclude irreversible fluoride inhibition of enolase.     

Involvement of glycolytic metabolism in developmental inhibition of rat two-cell embryos by phosphate

To elucidate the mechanism by which phosphate induces developmental inhibition of rat 2-cell embryos, we examined the mutual effects of glucose and other glycolytic and non-glycolytic sugars, the non-metabolizable glucose analogue, and glycolytic inhibitors on the inhibitory effect of phosphate. In the absence of glucose, 30-49% of embryos treated with 10-500 microM phosphate were able to develop to morula and blastocysts. On the other hand, in the presence of 5 mM glucose, 10 microM phosphate decreased the developmental rate of 2-cell embryos to the 4-cell stage and completely inhibited the development beyond the 4-cell stage. In contrast, glucose showed no influence on development in phosphate-free medium. Similarly to glucose, the other glycolytic sugars fructose (5 mM) and mannose (5 mM) enhanced the inhibitory effect of 10 microM phosphate but had no influence in the absence of phosphate. In contrast, the non-glycolytic sugar and non-metabolizable glucose analogue N-acetylglucosamine and 3-O-methylglucose (3-O-MGlc), respectively, did not enhance the effects of phosphate. 2-Deoxyglucose (2DGlc), another glucose analogue that is non-metabolizable but is converted by hexokinase to 2DGlc 6-phosphate, at concentrations as low as 0.1 mM completely inhibited cell cycle progression of 2-cell embryos cultured in glucose-free (Glc(-)) medium with 10 microM phosphate. In contrast, in the absence of phosphate, 2DGlc at the same concentration allowed 55% of 2-cell embryos to develop to morula and blastocyst stages. Addition of an inhibitor of enolase in glycolysis, sodium fluoride (NaF), at 1 mM to the Glc(-) medium also enhanced the inhibitory effects of 10 microM phosphate, whereas 1 mM NaF in the absence of phosphate showed no inhibitory effects on the development of 2-cell embryos to morula and blastocyst stages. From these results, disturbance of glycolysis is a critical reason for the developmental inhibition caused by phosphate in early rat embryos in culture.     

Inhibition of human muscle-specific enolase by methylglyoxal and irreversible formation of advanced glycation end products

Methylglyoxal (MG) was studied as an inhibitor and effective glycating factor of human muscle-specific enolase. The inhibition was carried out by the use of a preincubation procedure in the absence of substrate. Experiments were performed in anionic and cationic buffers and showed that inhibition of enolase by methylglyoxal and formation of enolase-derived glycation products arose more effectively in slight alkaline conditions and in the presence of inorganic phosphate. Incubation of 15 micromolar solutions of the enzyme with 2 mM, 3.1 mM and 4.34 mM MG in 100 mM phosphate buffer pH 7.4 for 3 h caused the loss a 32%, 55% and 82% of initial specific activity, respectively. The effect of MG on catalytic properties of enolase was investigated. The enzyme changed the K(M) value for glycolytic substrate 2-phospho-D-glycerate (2-PGA) from 0.2 mM for native enzyme to 0.66 mM in the presence of MG. The affinity of enolase for gluconeogenic substrate phosphoenolpyruvate altered after preincubation with MG in the same manner, but less intensively. MG has no effect on V(max) and optimal pH values. Incubation of enolase with MG for 0-48 h generated high molecular weight protein derivatives. Advanced glycation end products (AGEs) were resistant to proteolytic degradation by trypsin. Magnesium ions enhanced the enzyme inactivation by MG and facilitated AGEs formation. However, the protection for this inhibition in the presence of 2-PGA as glycolytic substrate was observed and AGEs were less effectively formed under these conditions.     

Kinetic modeling of oligosaccharide synthesis catalyzed by leuconostoc mesenteroides NRRL B-1299 dextransucrase

The kinetic behavior of soluble and insoluble forms of dextransucrase from Leuconostoc mesenteroides NRRL B-1299 was investigated with sucrose as substrate and maltose as acceptor. To study the parameters involved, a kinetic model was applied that was previously developed for L. mesenteroides NRRL B-512F dextransucrase. There are significant correlations between the parameters of the soluble form of B-1299 dextransucrase and those calculated for the B-512F enzyme; that is, their properties are comparable and differ from those of the insoluble form of B-1299 dextransucrase. Whereas the calculated parameters for high maltose concentrations describe the kinetic behavior very well, the time curves for low maltose concentrations were not described correctly. Therefore, the parameters were calculated separately for the two ranges. Copyright 1999 John Wiley & Sons, Inc.     

Inhibition of human muscle-specific enolase by methylglyoxal and irreversible formation of advanced glycation end products

Methylglyoxal (MG) was studied as an inhibitor and effective glycating factor of human muscle-specific enolase. The inhibition was carried out by the use of a preincubation procedure in the absence of substrate. Experiments were performed in anionic and cationic buffers and showed that inhibition of enolase by methylglyoxal and formation of enolase-derived glycation products arose more effectively in slight alkaline conditions and in the presence of inorganic phosphate. Incubation of 15 micromolar solutions of the enzyme with 2 mM, 3.1 mM and 4.34 mM MG in 100 mM phosphate buffer pH 7.4 for 3 h caused the loss a 32%, 55% and 82% of initial specific activity, respectively. The effect of MG on catalytic properties of enolase was investigated. The enzyme changed the K_M value for glycolytic substrate 2-phospho-D-glycerate (2-PGA) from 0.2 mM for native enzyme to 0.66 mM in the presence of MG. The affinity of enolase for gluconeogenic substrate phosphoenolpyruvate altered after preincubation with MG in the same manner, but less intensively. MG has no effect on V_max and optimal pH values. Incubation of enolase with MG for 0-48 h generated high molecular weight protein derivatives. Advanced glycation end products (AGEs) were resistant to proteolytic degradation by trypsin. Magnesium ions enhanced the enzyme inactivation by MG and facilitated AGEs formation. However, the protection for this inhibition in the presence of 2-PGA as glycolytic substrate was observed and AGEs were less effectively formed under these conditions.     

Novel oligosaccharides synthesized from sucrose donor and cellobiose acceptor by alternansucrase

Cellobiose was tested as acceptor in the reaction catalyzed by alternansucrase (EC 2.4.1.140) from Leuconostoc mesenteroides NRRL B-23192. The oligosaccharides synthesized were compared to those obtained with dextransucrase from L. mesenteroides NRRL B-512F. With alternansucrase and dextransucrase, overall oligosaccharide synthesis yield reached 30 and 14%, respectively, showing that alternansucrase is more efficient than dextransucrase for cellobiose glucosylation. Interestingly, alternansucrase produced a series of oligosaccharides from cellobiose. Their structure was determined by mass spectrometry and [13C-1H] NMR spectroscopy. Two trisaccharides are first produced: alpha-D-glucopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->4)]-D-glucopyranose (compound A) and alpha-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl-(1-->4)-D-glucopyranose (compound B). Then, compound B can in turn be glucosylated leading to the synthesis of a tetrasaccharide with an additional alpha-(1-->6) linkage at the non-reducing end (compound D). The presence of the alpha-(1-->3) linkage occurred only in the pentasaccharides (compounds C1 and C2) formed from tetrasaccharide D. Compounds B, C1, C2 and D were never described before. They were produced efficiently only by alternansucrase. Their presence emphasizes the difference existing in the acceptor reaction selectivity of the various glucansucrases.     

Molecular modelling, docking and interaction studies of human-plasmogen and salmonella enolase with enolase inhibitors

Salmonella enteric serovar Typhi Ty2 is a human specific pathogen and an etiological agent for typhoid fever. Most of Salmonella serotypes produce glycogen which has a comparatively minor role in virulence and colonization, but has a more significant role in survival. Enzymes present in glycolytic pathway of bacteria help bacteria to survive by activating other factors inside host. Numerous pathogenic bacteria species intervene with the plasminogen system, and this plasminogen-enolase association may play a critical role in the virulence of S. Typhi by causing direct damage to the host cell extracellular matrix, possibly by enzymic degradation of extracellular matrix proteins or other protein constituents. In this study, molecular modelling of enolase of Salmonella has been accomplished in silico by comparative modelling; we have then analyzed Human alpha enolase which is a homodimer and serves on epithelial cells with our model. Both Structures were docked by D-tartronate semialdehyde phosphate (TSP) and 3-aminoenolpyruvate phosphate (AEP) enolase inhibitors. Our study shows that salmonella enolase and human enolase have different active sites in their structure. This will help in development of new ligands, more suitable for inhibiting bacterial survival inside host as vaccines for typhoid fever are not fully protective. The study also confirmed that enolase Salmonella and Human Plasminogen suggested direct physical interaction between both of them as the activation loop of plasminogen residues showed conformational changes similar to the tissue type plasminogen activator. Various computational biology tools were used for our present study such as Modeller, Molegro Virtual Docker, Grommacs.     

A protein phosphatase associated with rat heavy gastric membranes enriched with (H+-K+)-ATPase influences membrane K+ transport activity

Rat stimulated heavy gastric membranes enriched with (H+-K+)-ATPase, a marker for the apical membrane of the parietal cell, displayed a 32P-histone-dephosphorylating activity which appeared to be physically copurified with, but functionally independent of, the ATPase. The protein phosphatase activity was optimal at pH 7.5 and was inhibited by fluoride (50 mM), inorganic phosphate (50 mM), and p-chloromercuribenzoate (0.1 mM), but was insensitive to vanadate (1 mM). The 32P-phosphoproteins in the heavy gastric membranes were also dephosphorylated, apparently by their own membrane-bound phosphatase in the presence of Mg2+ at millimolar concentrations, which is likely to enhance membrane-membrane interaction. Heavy gastric membrane vesicles incubated with Mg2+ (2 mM) exhibited no alterations in K+-dependent ATP-hydrolyzing activity, Cl permeability, and protein and lipid compositions, but irreversibly lost the ATP, K+-dependent H+-pumping activity. Since valinomycin, a K+-specific ionophore, restored the intravesicular acidifying activity and an inhibitor of the protein phosphatase, inorganic phosphate, largely blocked the Mg2+-induced change in the membrane transport function, it is reasonable to propose that the phosphatase action on certain membrane proteins, possibly the putative K+ transporter or regulatory proteins, selectively decreases K+-conductance in the apical membranes of gastric parietal cells.     

Production and secretion of recombinant Leuconostoc mesenteroides dextransucrase DsrS in Bacillus megaterium

Leuconostoc mesenteroides dextransucrase DsrS was recombinantly produced in Bacillus megaterium and exported into the growth medium. For this purpose a plasmid-based xylose-inducible gene expression system was optimized via introduction of a multiple cloning site and an encoded optimal B. megaterium ribosome binding site. A cre mediating glucose-dependent catabolite repression was removed. Recombinant DsrS was found in the cytoplasm and exported via its native leader sequence into the growth medium. Elimination of the extracellular protease NprM increased extracellular DsrS concentrations by a factor of 4 and stabilized the recombinant protein for up to 12 h. Cultivation in a semi-defined medium resulted in a further doubling of extracellular DsrS concentration up to an activity of 65 Units/L. To develop an industrial process a high cell density cultivation of B. megaterium was established yielding cell dry weights of up to 80 g/L. After induction of dsrS expression high specific (362 Units/g) and volumetric (28,600 Units/L) activities of dextran free DsrS were measured. However, using high cell density cultivation, most DsrS was found cell-associated indicating current limitations of the production process. A protease accessibility assay identified the major limitation of DsrS production at the level of protein folding. Intracellular misfolding of DsrS hampered DsrS export via the SEC pathway at high cell densities. The subsequent use of a semi-defined mineral medium and the induction of DsrS production at lower cell densities increased protein export efficiency remarkably, but also led to extracellular DsrS aggregation. Further optimization strategies for the production of recombinant DsrS in B. megaterium are discussed.     

Effects of Tween 80 and sodium fluoride on extracellular glucosyltransferase production and membrane lipids of Streptococcus mutans

1. Both Tween 80 and sodium fluoride significantly enhanced total extracellular glucosyltransferase activities of Streptococcus mutans. 2. Water-insoluble and water-soluble glucan formation were uniformly increased by Tween 80, whereas fluoride stimulated only water-soluble glucan formation. 3. Elevated glucan formation was due to an increase in enzymes secreted from bacterial cells. 4. Fatty acid composition and phospholipid content in bacterial membrane were changed by Tween 80, although sodium fluoride scarcely showed these changes. 5. Comparative results suggest that modulation of membrane lipids participates in mutansucrase production but not in dextransucrase production of S. mutans.     

Growth inhibition of Streptococcus mutans and Leuconostoc mesenteroides by sodium fluoride and ionic tin.

Sodium fluoride caused inhibition of growth rate and growth levels of Streptococcus mutans with glucose as the primary energy and carbon source. Stannous fluoride increased growth lag nad caused a much greater inhibition of growth rate than did sodium fluoride. Neither compound was found to be bactericidal when culture viability was measured after 6 days of incubation. Leuconostoc mesenteroides, which lacks a phosphotransferase system for sugar transport, showed less inhibition of growth rate with both inhibitors than did S. mutans, which possesses a phosphotransferase system. Metabolism of glucose or lactose which requires enolase activity shoed sodium fluoride inhibition, whereas metabolism of arginine or pyruvate does not involve enolase activity and showed no inhibition of growth.     

The cathepsin B of Toxoplasma gondii,toxopain-1, is critical for parasite invasion and rhoptry protein processing

Cysteine proteinases play a major role in invasion and intracellular survival of a number of pathogenic parasites. We cloned a single copy gene, tgcp1, from Toxoplasma gondii and refolded recombinant enzyme to yield active proteinase. Substrate specificity of the enzyme and homology modeling identified the proteinase as a cathepsin B. Specific cysteine proteinase inhibitors interrupted invasion by tachyzoites. The T. gondii cathepsin B localized to rhoptries, secretory organelles required for parasite invasion into cells. Processing of the pro-rhoptry protein 2 to mature rhoptry proteins was delayed by incubation of extracellular parasites with a cathepsin B inhibitor prior to pulse-chase immunoprecipitation. Delivery of cathepsin B to mature rhoptries was impaired in organisms with disruptions in rhoptry formation by expression of a dominant negative micro1-adaptin. Similar disruption of rhoptry formation was observed when infected fibroblasts were treated with a specific inhibitor of cathepsin B, generating small and poorly developed rhoptries. This first evidence for localization of a cysteine proteinase to the unusual rhoptry secretory organelle of an apicomplexan parasite suggests that the rhoptries may be a prototype of a lysosome-related organelle and provides a critical link between cysteine proteinases and parasite invasion for this class of organism.     

Identification, effective purification and functional characterization of dextransucrase from Leuconostoc mesenteroides NRRL B-640

The extracellular dextransucrase from Leuconostoc mesenteroides NRRL B-640 was purified using polyethylene glycol fractionation (PEG) and gel-filtration. The cell free extract was subjected to fractionation by PEG-200, 400 and 1500. The 10% (w/v) PEG-1500 gave dextransucrase with maximum specific activity of 23 with 40 fold purification in a single step. The purified enzyme showed multiple molecular forms on SDS-PAGE, however the same sample showed a single band on non-denaturing native-PAGE. The purified dextransucrase fractions obtained from PEG-1500, confirmed the presence of dextran, when run on SDS-PAGE under non-denaturing gels for in situ activity detection by Periodic Acid Schiff's staining. The activity bands corresponded to the native and active form of the purified dextransucrase of approximately, 180kDa molecular size, that appeared on the denaturing gels stained with Coomassie Brilliant Blue. No bands appeared after staining the activity of dextransucrase on non denaturing SDS-PAGE gels with raffinose, which excluded the presence of fructosyltransferases. Further purification of 10% PEG-1500 purified dextransucrase by gel-filtration gave dextransucrase with specific activity of 35 with 61 fold purification.