1-kestose and 6-kestose

Oligosaccharides may have beneficial properties of the prevention of atopic dermatitis (AD). Kestose, a fructo-oligosaccharide, stimulates the activity of bifidobacteria.. To assess the clinical effect of kestose on the treatment of AD in infants.. A randomized, double-blind, placebo-controlled trial was carried out using 15 and 14 infants with AD in the kestose group and placebo groups, respectively. One to 2 g kestose and maltose were administered to the subjects in the kestose and placebo groups, respectively, everyday for 12 weeks. Clinical evaluations of AD using Severity Scoring of Atopic Dermatitis (SCORAD) and the enumeration of bifidobacteria in the feces using real-time PCR were performed at Weeks 0, 6, and 12.. The medians of the SCORAD score were significantly lower in the kestose group than in the placebo group on both Week 6 (25.3 vs. 36.4; P=0.004) and Week 12 (19.5 vs. 37.5; P<0.001). No significant correlation was found between the improvement of the SCORAD score and the count of bifidobacteria.. Kestose was found to exert a beneficial effect on the clinical symptoms in infants with AD. The mechanism how does kestose improve the symptoms of AD remains to be elucidated.

Topics: Bifidobacterium; Child, Preschool; Dermatitis, Atopic; Double-Blind Method; Feces; Female; Humans; Infant; Infant, Newborn; Male; Maltose; Sweetening Agents; Time Factors; Trisaccharides

Under specific reaction conditions, levansucrase from Bacillus subtilis (SacB) catalyzes the synthesis of a low molecular weight levan through the non-processive elongation of a great number of intermediates. To deepen understanding of the polymer elongation mechanism, we conducted a meticulous examination of the fructooligosaccharide profile evolution during the levan synthesis. As a result, the formation of primary and secondary intermediates series in different reaction stages was observed. The origin of the series was identified through comparison with product profiles obtained in acceptor reactions employing levanbiose, blastose, 1-kestose, 6-kestose, and neo-kestose, and supported with the isolation and NMR analyses of some relevant products, demonstrating that all of them are inherent products during levan formation from sucrose. These results allowed to establish the network of fructosyl transfer reactions involved in the non-processive levan synthesis. Overall, our results reveal how the relaxed acceptor specificity of SacB during the initial steps of the synthesis is responsible for the formation of several levan series, which constitute the final low molecular weight levan distribution.

Topics: Bacillus subtilis; Catalysis; Disaccharidases; Disaccharides; Fructans; Hexosyltransferases; Kinetics; Molecular Weight; Oligosaccharides; Sucrose; Trisaccharides

Fructans play important roles as reserve carbohydrates and stress protectants in plants, and additionally serve as prebiotics with emerging antioxidant properties. Various fructan types are synthesized by an array of plant fructosyltransferases belonging to family 32 of the glycoside hydrolases (GH32), clustering together with GH68 in Clan-J. Here, the 3D structure of a plant fructosyltransferase from a native source, the Pachysandra terminalis 6-SST/6-SFT (Pt6-SST/6-SFT), is reported. In addition to its 1-SST (1-kestose-forming) and hydrolytic side activities, the enzyme uses sucrose to create graminan- and levan-type fructans, which are probably associated with cold tolerance in this species. Furthermore, a Pt6-SST/6-SFT complex with 6-kestose was generated, representing a genuine acceptor binding modus at the +1, +2 and +3 subsites in the active site. The enzyme shows a unique configuration in the vicinity of its active site, including a unique D/Q couple located at the +1 subsite that plays a dual role in donor and acceptor substrate binding. Furthermore, it shows a unique orientation of some hydrophobic residues, probably contributing to its specific functionality. A model is presented showing formation of a β(2-6) fructosyl linkage on 6-kestose to create 6,6-nystose, a mechanism that differs from the creation of a β(2-1) fructosyl linkage on sucrose to produce 1-kestose. The structures shed light on the evolution of plant fructosyltransferases from their vacuolar invertase ancestors, and contribute to further understanding of the complex structure-function relationships within plant GH32 members.

Topics: Amino Acid Sequence; Binding Sites; Catalytic Domain; Crystallography, X-Ray; Fructans; Hexosyltransferases; Kinetics; Models, Molecular; Molecular Sequence Data; Pachysandra; Plant Proteins; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary; Sequence Homology, Amino Acid; Substrate Specificity; Trisaccharides

Schwanniomyces occidentalis β-fructofuranosidase (Ffase) releases β-fructose from the nonreducing ends of β-fructans and synthesizes 6-kestose and 1-kestose, both considered prebiotic fructooligosaccharides. Analyzing the amino acid sequence of this protein revealed that it includes a serine instead of a leucine at position 196, caused by a nonuniversal decoding of the unique mRNA leucine codon CUG. Substitution of leucine for Ser196 dramatically lowers the apparent catalytic efficiency (k(cat)/K(m)) of the enzyme (approximately 1,000-fold), but surprisingly, its transferase activity is enhanced by almost 3-fold, as is the enzymes' specificity for 6-kestose synthesis. The influence of 6 Ffase residues on enzyme activity was analyzed on both the Leu196/Ser196 backgrounds (Trp47, Asn49, Asn52, Ser111, Lys181, and Pro232). Only N52S and P232V mutations improved the transferase activity of the wild-type enzyme (about 1.6-fold). Modeling the transfructosylation products into the active site, in combination with an analysis of the kinetics and transfructosylation reactions, defined a new region responsible for the transferase specificity of the enzyme.

Topics: Amino Acid Sequence; Amino Acid Substitution; beta-Fructofuranosidase; Codon; DNA, Fungal; Fructans; Kinetics; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutation, Missense; Saccharomycetales; Sequence Analysis, DNA; Trisaccharides

Biosynthesis of fructo-oligosaccharides (FOS) was observed during growth of the thermophilic fungus Sporotrichum thermophile on media containing high sucrose concentrations. Submerged batch cultivation with the optimum initial sucrose concentration of 250 g/l allowed the production of 12.5 g FOS/l. The FOS mixture obtained was composed of three sugars, which were isolated by size-exclusion chromatography. They were characterized by acid hydrolysis and HPLC as 1-kestose, 6-kestose and neokestose. The mechanism of osmotic adaptation of S. thermophile was investigated and sugars and amino acids were found to be the predominant compatible solutes. The fungus accumulated glutamic acid, arginine, alanine, leucine and lysine, in order to balance the outer osmotic pressure. Fatty acid analysis of the membrane lipids showed a relatively high percentage of unsaturated lipids, which is known to be associated with high membrane fluidity.

Topics: Amino Acids; Carbohydrates; Cell Membrane; Chromatography, High Pressure Liquid; Culture Media; Cytoplasm; Hydrogen-Ion Concentration; Membrane Fluidity; Membrane Lipids; Oligosaccharides; Osmotic Pressure; Sporothrix; Sucrose; Trisaccharides