turanose and isomaltulose

In the daily diet, sweeteners play an indispensable role. Among them, sucrose, a widely occurring disaccharide in nature, is a commonly used sweetener. However, the intake of sucrose can cause a rapid increase in blood glucose, which leads to a number of health problems. Therefore, there is an urgent need for possible alternatives to sucrose. Currently, four naturally occurring sucrose isomers, trehalulose, turanose, leucrose, and isomaltulose are considered to be possible alternatives to sucrose due to their suitable sweetness, potential physiological benefits, and feasible production processes. This review covers the properties of these alternative sweeteners, including their structure, sweetness, hydrolysis rate, toxicology, and cariogenicity, and exhibits their potential applications in chronic diseases management, anti-inflammatory supplement, prebiotic dietary supplement, and stabilizing agent. The biosynthesis of these sucrose isomers using carbohydrate-active enzymes and their industrial production processes are also systematically summarized.

Topics: Diet; Disaccharides; Food; Humans; Isomaltose; Isomerism; Sucrose; Sweetening Agents; Taste

Trehalose supports the growth of Thermus thermophilus strain HB27, but the absence of obvious genes for the hydrolysis of this disaccharide in the genome led us to search for enzymes for such a purpose. We expressed a putative alpha-glucosidase gene (TTC0107), characterized the recombinant enzyme, and found that the preferred substrate was alpha,alpha-1,1-trehalose, a new feature among alpha-glucosidases. The enzyme could also hydrolyze the disaccharides kojibiose and sucrose (alpha-1,2 linkage), nigerose and turanose (alpha-1,3), leucrose (alpha-1,5), isomaltose and palatinose (alpha-1,6), and maltose (alpha-1,4) to a lesser extent. Trehalose was not, however, a substrate for the highly homologous alpha-glucosidase from T. thermophilus strain GK24. The reciprocal replacement of a peptide containing eight amino acids in the alpha-glucosidases from strains HB27 (LGEHNLPP) and GK24 (EPTAYHTL) reduced the ability of the former to hydrolyze trehalose and provided trehalose-hydrolytic activity to the latter, showing that LGEHNLPP is necessary for trehalose recognition. Furthermore, disruption of the alpha-glucosidase gene significantly affected the growth of T. thermophilus HB27 in minimal medium supplemented with trehalose, isomaltose, sucrose, or palatinose, to a lesser extent with maltose, but not with cellobiose (not a substrate for the alpha-glucosidase), indicating that the alpha-glucosidase is important for the assimilation of those four disaccharides but that it is also implicated in maltose catabolism.

Topics: alpha-Glucosidases; Bacterial Proteins; Disaccharides; Isomaltose; Kinetics; Maltose; Mutagenesis, Site-Directed; Phenotype; Recombinant Proteins; Substrate Specificity; Sucrose; Thermus thermophilus; Trehalose

To gain insight into the regulatory mechanisms of sugar signaling in plants, the effect of derivatives of the transport sugar sucrose (Suc), the Suc isomers palatinose and turanose, and the Suc analog fluoro-Suc were tested. Photo-autotrophic suspension culture cells of tomato (Lycopersicon peruvianum) were used to study their effect on the regulation of marker genes of source and sink metabolism, photosynthesis, and the activation of mitogen-activated protein kinases (MAPKs). Suc and glucose (Glc) resulted in reverse regulation of source and sink metabolism. Whereas the mRNA level of extracellular invertase (Lin6) was induced, the transcript level of small subunit of ribulose bisphosphate carboxylase (RbcS) was repressed. In contrast, turanose, palatinose, and fluoro-Suc only rapidly induced Lin6 mRNA level, whereas the transcript level of RbcS was not affected. The differential effect of the metabolizable and non-metabolizable sugars on RbcS mRNA regulation was reflected by the fact that only Suc and Glc inhibited photosynthesis and chlorophyll fluorescence. The activation of different signal transduction pathways by sugars was further supported by the analysis of the activation of MAPKs. MAPK activity was found to be strongly activated by turanose, palatinose, and fluoro-Suc, but not by Suc and Glc. To analyze the role of sugars in relation to pathogen perception, an elicitor preparation of Fusarium oxysporum lycopersici was used. The strong activation of MAPKs and the fast and transient induction of Lin6 expresssion by the fungal elicitor resembles the effect of turanose, palatinose, and fluoro-Suc and indicates that non-metabolizable sugars are sensed as stress-related stimuli.

Topics: beta-Fructofuranosidase; Carbohydrate Metabolism; Cells, Cultured; Chlorophyll; Disaccharides; Enzyme Activation; Fusarium; Gene Expression Regulation, Enzymologic; Glucose; Glycoside Hydrolases; Isomaltose; Mitogen-Activated Protein Kinases; Oxygen; Photosynthesis; Plant Proteins; Protein Serine-Threonine Kinases; Ribulose-Bisphosphate Carboxylase; RNA, Messenger; Signal Transduction; Solanum lycopersicum; Sucrose

A behavioural study on the ant Lasius niger was performed by observing its feeding responses to 85 compounds presented in a two-choice situation (tested compound versus water control or sucrose solution). Among these compounds, only 21 were phagostimulating: six monosaccharides (D-glucose, 6-deoxy-D-glucose, L-galactose, L-fucose, D-fructose, L-sorbose), four derivatives of D-glucose (methyl alpha-D-glucoside, D-gluconolactone and 6-chloro- and 6-fluoro-deoxy-D-glucose), five disaccharides (sucrose, maltose, palatinose, turanose and isomaltose), one polyol glycoside (maltitol), three trisaccharides (melezitose, raffinose and maltotriose) and two polyols (sorbitol and L-iditol). None of the 16 non-carbohydrate non-polyol compounds tested, although perceived as sweet in humans, was found to be active in ants. The molar order of effectiveness of the major naturally occuring compounds (melezitose > sucrose = raffinose > D-glucose > D-fructose = maltose = sorbitol) is basically different from the molar order of their sweetness potency in humans (sucrose > D-fructose > melezitose > maltose > D-glucose = raffinose = sorbitol). On a molar basis melezitose is in L. niger about twice as effective as sucrose or raffinose, while D-glucose and D-fructose are three and four times less effective, respectively, than sucrose or raffinose. From a structure-activity relationship study it was inferred that the active monosaccharides and polyols should interact with the ant receptor through only one type of receptor, through the same binding pocket and the same binding residues, via a six-point interaction. The high effectiveness of melezitose in L. niger mirrors the feeding habits of these ants, which attend homopterans and are heavy feeders on their honeydew, which is very rich in this carbohydrate.

Topics: Animals; Ants; Deoxyglucose; Disaccharides; Fructose; Fucose; Galactose; Glucose; Humans; Isomaltose; Maltose; Models, Chemical; Raffinose; Sorbitol; Sorbose; Structure-Activity Relationship; Sugar Alcohols; Taste; Trisaccharides

Not only sucrose but the five isomeric alpha-D-glucosyl-D-fructoses trehalulose, turanose, maltulose, leucrose, and palatinose are utilized by Klebsiella pneumoniae as energy sources for growth, thereby undergoing phosphorylation by a phosphoenolpyruvate-dependent phosphotransferase system uniformly at 0-6 of the glucosyl moiety. Similarly, maltose, isomaltose, and maltitol, when exposed to these conditions, are phosphorylated regiospecifically at O-6 of their non-reducing glucose portion. The structures of these novel compounds have been established unequivocally by enzymatic analysis, acid hydrolysis, FAB negative-ion spectrometry, and 1H and 13C NMR spectroscopy. In cells of K. pneumoniae, hydrolysis of sucrose 6-phosphate is catalyzed by sucrose 6-phosphate hydrolase from Family 32 of the glycosylhydrolase superfamily. The five 6'-O-phosphorylated alpha-D-glucosyl-fructoses are hydrolyzed by an inducible (approximately 49-50 Kda) phospho-alpha-glucosidase from Family 4 of the glycosylhydrolase superfamily.

Topics: alpha-Glucosidases; Amino Acid Sequence; beta-Fructofuranosidase; Carbohydrate Conformation; Chromatography, Thin Layer; Disaccharides; Fructose; Glycoside Hydrolases; Hydrolysis; Immunoblotting; Isomaltose; Isomerism; Klebsiella pneumoniae; Magnetic Resonance Spectroscopy; Molecular Sequence Data; Molecular Structure; Phosphorylation; Sucrose

alpha-Glucosidase II of the facultative thermophile Bacillus thermoamyloliquefaciens KP1071 (FERM-P8477; growth over 30-66 degrees C) was purified to a homogeneous state. Its M(r) was estimated as 90000 by SDS/PAGE. However, the enzyme behaved as an active Mr 540000 protein on gel filtration with each of two gels of different matrices as well as on gel electrophoresis under native conditions. The enzyme was not glycosylated. Its isoelectric point was estimated as 5.7. The N-terminal sequence of 20 residues was determined asAla1-Ile-Gln-Pro-Glu-Gln-Asp-Asp-Lys-Thr-Gln-Glu-Asp-Gly- Tyr-Ile-Asp-Ile-Gly-Asn20. The sequence did not resemble those of procaryotic and eucaryotic proteins hitherto reported including the monomeric exo-alpha-1,4-glucosidase and the monomeric oligo-1,6-glucosidase from the same microorganism. The alpha-glucosidase II had no antigenic group shared with the latter two enzymes. Analysis of substrate specificity showed that the alpha-glucosidase II has dual activity towards oligo-1,6-glucosidases and exo-alpha-1,4-glucosidases, but its preference is for non-reducing terminal alpha-1,4 glucosidic bonds in substrates. Kinetic studies proved that both activities are attributed to the same catalytic site. The enzyme was most active at 81 degrees C and pH 7.0. Its half-life at pH 6.8 was 10 min at 81 degrees C, and 5 h at 55 degrees C in 6.4 M urea, 26% ethanol or 2.5% SDS. We suggest that the alpha-glucosidase II is a thermostable, homohexameric enzyme of origin distinct from the exo-alpha-1,4-glucosidase and the oligo-1,6-glucosidase present in the same strain.

Topics: alpha-Glucosidases; Amino Acids; Bacillus; Binding Sites; Disaccharides; Electrophoresis, Polyacrylamide Gel; Enzyme Stability; Glucans; Hydrogen-Ion Concentration; Immunodiffusion; Isomaltose; Kinetics; Maltose; Molecular Weight; Oligo-1,6-Glucosidase; Oligosaccharides; Temperature; Trisaccharides

Dispirodioxanyl pseudotetrasaccharides 6-O-alpha-D-glucopyranosyl-alpha-D-fructofuranose 6-O-alpha-D-glucopyranosyl-beta-D-fructofuranose 1,2':2,1'-dianhydride, 5-O-alpha-D-glucopyranosyl-alpha-D-fructopyranose 5-O-alpha-D-glucopyranosyl-beta-D-fructopyranose 1,2':2,1'-dianhydride, 4-O-alpha-D-glucopyranosyl-alpha-D-fructofuranose 4-O-alpha-D-glucopyranosyl-beta-D-fructopyranose 1,2':2,1'-dianhydride, 4-O-beta-D-galactopyranosyl-alpha-D-fructofuranose 4-O-beta-D-galactopyranosyl-beta-D-fructopyranose 1,2':2,1'-dianhydride, and 3-O-alpha-D-glucopyranosyl-alpha-D-fructofuranose 3-O-alpha-D-glucopyranosyl-beta-D-fructofuranose 1,2':2,1'-dianhydride were respectively obtained, on a preparative scale, by dissolution of the isomeric glycosylfructoses palatinose, leucrose, maltulose, lactulose, and turanose in anhydrous hydrogen fluoride. The reaction, involving selective protonation at the free anomeric position of the fructose unit, was extended to the preparation of the pseudotrisaccharides 6-O-alpha-D-glucopyranosyl-alpha-D-fructofuranose beta-D-fructopyranose 1,2':2',1-dianhydride from palatinose and fructose, and to its 3-O-, 4-O-, and 4'-O-glucosyl analogues using turanose and maltulose as the disaccharide precursor. The cross-reactions of palatinose with maltulose and with leucrose resulted in the preparation of 6-O-alpha-D-glucopyranosyl-alpha-D-fructofuranose 4-O-alpha-D-glucopyranosyl-beta-D-fructopyranose 1,2':2,1'-dianhydride and 6-O-alpha-D-glucopyranosyl-alpha-D-fructofuranose 5-O-alpha-D-glucopyranosyl-beta-D-fructopyranose 1,2':2,1'-dianhydride, respectively.

Topics: Anhydrides; Carbohydrate Sequence; Dioxanes; Disaccharides; Hydrofluoric Acid; Isomaltose; Isomerism; Lactulose; Molecular Sequence Data; Oligosaccharides; Protons

Selective activation of the ketose unit in the isomeric glycosylfructoses, palatinose, leucrose, maltulose, turanose and lactulose, with pyridinium poly(hydrogen fluoride) resulted in the almost quantitative formation of glycosylated difructose dianhydrides. The reaction preferentially involves a reactive fructofuranosyl oxocarbenium ion and is subject to stereoelectronic control. The relative amounts of isomeric spirodioxanyl oligosaccharides obtained within a series was shown to depend on the reaction conditions, especially on the hydrogen fluoride-pyridine ratio. Using suitable concentrations of hydrogen fluoride in pyridine, the reaction was easily directed to the formation of the kinetic difuranosyl or thermodynamic pyranosyl derivatives. More rigorous conditions resulted in the specific hydrolysis of one glycosidic bond in the tetrasaccharides derived from palatinose, leucrose and turanose, to yield spirodioxanyl trisaccharides.

Topics: Anhydrides; Carbohydrate Sequence; Disaccharides; Fructose; Hydrofluoric Acid; Isomaltose; Lactulose; Molecular Sequence Data; Oligosaccharides; Protons; Pyridinium Compounds; Stereoisomerism