Journal of applied glycoscience最新文献

Bifidobacterium longum subsp. infantis ATCC 15697 possesses five α-L-fucosidases, which have been previously characterized toward fucosylated human milk oligosaccharides containing α1,2/3/4-linked fucose [Sela et al.: Appl. Environ. Microbiol., 78, 795-803 (2012)]. In this study, two glycoside hydrolase family 29 α-L-fucosidases out of five (Blon_0426 and Blon_0248) were found to be 1,6-α-L-fucosidases acting on core α1,6-fucose on the N-glycan of glycoproteins. These enzymes readily hydrolyzed p-nitrophenyl-α-L-fucoside and Fucα1-6GlcNAc, but hardly hydrolyzed Fucα1-6(GlcNAcβ1-4)GlcNAc, suggesting that they de-fucosylate Fucα1-6GlcNAcβ1-Asn-peptides/proteins generated by the action of endo-β- N-acetylglucosaminidase. We demonstrated that Blon_0426 can de-fucosylate Fucα1-6GlcNAc-IgG prepared from Rituximab using Endo-CoM from Cordyceps militaris. To generate homogenous non-fucosylated N-glycan-containing IgG with high antibody-dependent cellular cytotoxicity (ADCC) activity, the resulting GlcNAc-IgG has a potential to be a good acceptor substrate for the glycosynthase mutant of Endo-M from Mucor hiemalis. Collectively, our results strongly suggest that Blon_0426 and Blon_0248 are useful for glycoprotein glycan remodeling.

We examined the in vitro digestibility of maltobionic acid, obtained from enzymatic oxidation of maltose, its utilization by intestinal bacteria, and its biological effects on the bowel movements in healthy subjects. We found that maltobionic acid is not digested in vitro by saliva, gastric juice, or pancreatic juice. Moreover, it is digested only to a small extent by small intestinal enzymes. Among the 24 strains of intestinal bacteria, maltobionic acid was selectively utilized by Bifidobacterium dentium and Bi. adolescentis. We also evaluated the influence of long-term ingestion of maltobionic acid calcium salt on bowel movements in healthy Japanese women by a randomized, double-blind, placebo-controlled, crossover trial. Thirty-four subjects completed the study, and no adverse events related to the test food were observed. Ten subjects were excluded prior to the efficacy analysis because of conflict with the control criteria; the remaining 24 subjects were analyzed. Intake of test food containing 4 g maltobionic acid for 4 weeks caused a significant increase in the stool frequency, significant improvement in stool form scale and CAS-MT total scores as compared with the placebo group. These results suggest that maltobionic acid is an indigestible carbohydrate and is a promising therapeutic agent for improving the intestinal environment.

The aim of this study was to investigate the effect of pH control by CO ₂ pressurization on the enzymatic hydrolysis of herbaceous feedstock in the calcium capturing by carbonation (CaCCO) process for fermentable sugar production. The pH of the slurry of 5 % (w/w) Ca(OH) ₂ -pretreated/CO ₂ -neutralized rice straw could be controlled between 5.70 and 6.38 at 50 °C by changing the CO ₂ partial pressure ( p CO ₂ ) from 0.1 to 1.0 MPa. A mixture of fungal enzyme preparations, namely, Trichoderma reesei cellulases/hemicellulases and Aspergillus niger β-glucosidase, indicated that pH 5.5-6.0 is optimal for solubilizing sugars from Ca(OH) ₂ -pretreated rice straw. Enzymatic saccharification of pretreated rice straw under various p CO ₂ conditions revealed that the highest soluble sugar yields were obtained at p CO ₂ 0.4 MPa and over, which is consistent with the expected pH at the p CO ₂ without enzymes and demonstrates the effectiveness of pH control by CO ₂ pressurization.

D-Allose (D-All), C-3 epimer of D-glucose, is a rare sugar known to suppress reactive oxygen species generation and prevent hypertension. We previously reported that D-allulose, a structural isomer of D-All, prolongs the lifespan of the nematode Caenorhabditis elegans. Thus, D-All was predicted to affect longevity. In this study, we provide the first empirical evidence that D-All extends the lifespan of C. elegans. Lifespan assays revealed that a lifespan extension was induced by 28 mM D-All. In particular, a lifespan extension of 23.8 % was achieved (p < 0.0001). We further revealed that the effects of D-All on lifespan were dependent on the insulin gene daf-16 and the longevity gene sir-2.1, indicating a distinct mechanism from those of other hexoses, such as D-allulose, with previously reported antiaging effects.

Rice-gel prepared by the following three steps: rice grain cooking, shearing of the cooked rice, and cooling for gel formation, is expected as a novel food ingredient for modification of various food products such as bread and noodles. To meet the demand for high-throughput systems for research and developments on the new rice gels, herein we established a mini-cooking system for preparation of rice gel samples from grains using a small-scale viscosity analyzer (Rapid Visco Analyzer; RVA). Polished rice grains (4 g) were cooked with 22 mL of water in a canister, and the paddle equipped in the canister was rotated at 2,000 rpm for 30 min (80 °C was used as a representative) to shear the cooked rice. The sheared paste was cooled to 10 °C at 160 rpm, and the initial gelation property was evaluated by viscosity analysis within the RVA. Alternatively, the sheared paste was transferred to an acrylic mold and kept at 4 °C for 0, 1, 3, and 5 days for determination of the hardness with a compression test. Compressive forces required to penetrate 20 % thickness for three tested rice cultivars were measured, and the trend of the value shifts during preservation is similar to the corresponding trend obtained in 300-g grain scale laboratory tests, whereas the individual values were halved in the former. This small cooking method could offer a useful assay system for a rapid evaluation in the breeding programs and in the high-throughput screening of additives for the modification of properties.

Lactulose, a keto-type disaccharide widely used in pharmaceuticals and functional foods, is produced by the isomerization of lactose. The organogermanium compound poly-trans-[(2-carboxyethyl) germasesquioxane] (Ge-132) is an effective reaction promoter for the conversion of lactose to lactulose because of its high affinity to ketoses. Herein, an effective method for the continuous production of lactulose syrup was developed using Ge-132 through the alkaline isomerization of lactose in a bench-scale plant. This plant carried out a continuous isomerization process using Ge-132, continuous two-step separation process for separating the sugar and Ge-132, a continuous purification and concentration processes for the lactulose syrup, and separation and purification processes for the recovery of Ge-132. In this bench-scale plant, lactulose-containing syrup (350 g/L lactulose, 92 g/L lactose, and 31 g/L galactose) was prepared. The syrup was produced at a rate of 37.7 mL/h, and the content of residual Ge-132 in the syrup was 2 mg/L. The separation process was a two-step separation system requiring an ordinary electrodialyzer and an electro deionizer, which allowed the separation of more than 99.6 % Ge-132 from the reaction mixture. Moreover, the majority of Ge-132 and sodium hydroxide were recovered through electrodialysis using a bipolar membrane. The proposed system is the first to represent the novel development of an effective continuous production system for lactulose-containing syrup on the basis of the use of organogermanium compounds and incorporation of the electrodialysis technology.

The carbohydrate esterase family 1 (CE1) in CAZy contains acetylxylan esterases (AXEs) and feruloyl esterases (FAEs). Here we cloned a gene coding for an AXE belonging to CE1 from Irpex lacteus (IlAXE1). IlAXE1 was heterologously expressed in Pichia pastoris, and the recombinant enzyme was purified and characterized. IlAXE1 hydrolyzed p-nitrophenyl acetate, α-naphthyl acetate and 4-methylumbelliferyl acetate, however, it did not show any activity on ethyl ferulate and methyl p-coumarate. We also examined the activity on partially acetylated and feruloylated xylan extracted from corncob by hydrothermal reaction. Similarly, ferulic and p-coumaric acids were not liberated, and acetic acid was only detected in the reaction mixture. The results indicated that IlAXE1 is an acetylxylan esterase actually reacted to acetyl xylan. However, since IlAXE1 was unable to completely release acetic acid esterifying xylopyranosyl residues, it is assumed that acetyl groups exhibiting resistance to deacetylation by IlAXE1 are present in corn cob xylan.

Ethanol precipitation process for purification of branched dextrin (BD) in Nägeli amylodextrin from waxy rice starch was developed. Temperature and ethanol concentration for precipitation were main parameters affecting the recovery and purity of BD, and the purification condition at 4 °C and 10 % (v/v) ethanol in water was adopted. After four-time precipitation, the BD recovery was 34.6 %, whereas the purity improved from 78.5 % at the initial to 94.5 % at the four-time purified BD (BD4). BD4 mainly showed a chain length distribution between 18 to 35 with a mode length of 25, which shifted after enzymatic debranching with isoamylase to that between 9 and 20 with a mode length of 14. Each purified BD was solubilized in water, and each solution was mixed with methanol-water at 25 °C to a final methanol concentration of 16 M. The flakes of BD precipitated with 16 M methanol exhibited an A-type crystal structure by an X-ray diffraction analysis, and the speed generation of white flakes in 16 M methanol dramatically increased as the purification time increased. The effect of addition of highly branched cyclic dextrin (HBCD) or sodium tetraborate on BD aggregation in 16 M methanol was also investigated, where the former retarded aggregation but the latter had no effect on the velocity. Thus, the purified BD enables rapid characterization of aggregation of double helix structures of A-type crystal structure, and screening of compounds which could affect the phenomena for prediction of potentials in starch modification as well.

We have developed a novel low-molecular-mass oil-gelling agent that is electrically neutral, has no nitrogen atoms and consists only of cyclic sugar alcohols and saturated linear fatty acids. The cyclic sugar alcohols were 1,5-anhydro-D-glucitol (1,5-AG) and 1,5-anhydro-D-mannitol (1,5-AM) derived from starch via 1,5-anhydro-D-fructose. Various saturated linear fatty acids with 10 to 18 and 22 carbon atoms were introduced into all the hydroxy groups of 1,5-AG. Various saturated linear fatty acids with 13 to 18 and 22 carbon atoms were introduced into all the hydroxy groups of 1,5-AM. Initially, the gelling ability increased as the carbon number increased, but the gelling ability decreased as the carbon number increased beyond 17 carbons. This trend was similar for both 1,5-AG and 1,5-AM. A comparison of 1,5-AG and 1,5-AM derivatives revealed that 1,5-AG derivatives had greater gelling abilities for different kinds of oils at the same fatty acid length. Further, it was confirmed by SEM observations that a three-dimensional fibrous structure was formed, and this network structure formed the gel and held the oil. Here, we report the synthesis and characteristics of a novel low-molecular-weight gelling agent and its gelation mechanism.

Glass transition temperature (T _g) is an important parameter for the physical quality control of hard candies. In order to understand the applicability of calcium maltobionate to hard candy, effect of calcium maltobionate addition on the T _g of model and hand-made hard candies was investigated. Freeze-dried calcium maltobionate-sugar (sucrose containing a small amount of glucose-fructose mixture) and calcium maltobionate-reduced isomaltulose mixtures were prepared as model candies, and their anhydrous T _g was evaluated using a differential scanning calorimetry. The anhydrous T _g increased linearly with the molar fraction of calcium maltobionate. From these results, it was expected that calcium maltobionate can improve the physical stability of normal and sugarless candies. For comparison, various commercial candies were employed, and their T _g was evaluated using a thermal rheological analysis. The T _g values were in the range of 28-49 °C. The T _g values were higher than 25 °C, which is significant with respect to the physical stability of the candies. Calcium maltobionate-sugar and calcium maltobionate-reduced isomaltulose candies were prepared as hand-made candies. The calcium maltobionate-reduced isomaltulose candies had higher T _g than the calcium maltobionate-sugar candies at each calcium maltobionate content, although reduced isomaltulose has a lower T _g than sugar. At a high calcium maltobionate content, calcium maltobionate-reduced isomaltulose candy had an equivalent T _g to the commercial sugarless candies, and thus practically acceptable stability was expected. In the case of calcium maltobionate-sugar candies, there was a possibility that the hydrolysis of sugar reduced their T _g. Vacuum-concentration will be useful to improve the T _g of the candies.