We screened for the carbohydrate-active enzymes that catalyze transglycosylation reactions on carboxylic compounds. Sucrose phosphorylase from Streptococcus mutans showed remarkable transglucosylating activity on benzoic acid, especially under acidic conditions. Sucrose phosphorylase from Leuconostoc mesenteroides also showed the activity, although it was very weak. Three main products were detected from the reaction mixture with sucrose, benzoic acid and S. mutans sucrose phosphorylase. These compounds were identified as 1-O-benzoyl α-D-glucopyranose, 2-O-benzoyl α-D-glucopyranose and 2-O-benzoyl β-D-glucopyranose on the basis of their isolation and the isolation of their acetylated products and subsequent spectroscopic analyses. Time-course analyses of the enzyme reaction and the degradation of 1-O-benzoyl α-D-glucopyranose proved that 1-O-benzoyl α-D-glucopyranose was initially produced by the transglucosylation reaction of the enzyme, and 2-O-benzoyl α-D-glucopyranose and 2-O-benzoyl β-D-glucopyranose were produced from 1-O-benzoyl α-D-glucopyranose by intramolecular acyl migration reaction. The acceptor specificity in the transglucosylation reaction of S. mutans sucrose phosphorylase was also examined. The enzyme could transglucosylate toward various carboxylic compounds. Comparison of the pH-dependence of transglucosylation activities of the enzyme on phosphate, hydroquinone and acetic acid suggest that an undissociated carboxylic group is essential as the acceptor molecule for the transglucosylation reaction on carboxylic compounds. We also obtained 1-O-acetyl α-D-glucopyranose using the transglucosylation reaction of the enzyme. The sensory test of acetic acid and the glucosides revealed that the sour taste of acetic acid was markedly reduced by glucosylation.
PURPOSE: Xanthophylls that exist in various vegetables and fruits have beneficial actions, such as antioxidant activity and an anti-metabolic syndrome effect, and daily intake of xanthophylls could play an important role in preventing lifestyle-related diseases. We investigated whether intake of xanthophylls from red paprika could decrease the abdominal fat area in the healthy overweight volunteers with a body mass index (BMI) ranging from 25 to < 30 kg/m2.
Phosphoryl oligosaccharides of calcium (POs-Ca) is a calcium salt of phosphoryl maltooligosaccharides made from potato starch. POs-Ca has high solubility in water and it can supply both calcium ion and acidic oligosaccharides in an aqueous medium. In this study, we evaluated effects of POs-Ca on cultured normal human epidermal keratinocytes (NHEK) and human skin. Several in vitro studies using cultured NHEK demonstrated that POs-Ca promoted NHEK differentiation, tight junction formation, intercellular lipid production, and gene expression involved in stratum corneum condition, skin barrier function and hydration. Skin penetration study using a three-dimensional epidermal model demonstrated that POs-Ca was able to provide both calcium ion and phosphoryl oligosaccharides to the epidermis. Furthermore, an in vivo study demonstrated that POs-Ca improved human skin conditions including hydration, barrier function, stratum corneum condition, and skin texture. These results suggest that POs-Ca can be a superior active agent for healthy epidermis.
Neopullulanase was the key enzyme to open the door for the formulation of the concept of the aamylasefamily. The enzyme catalyzes both hydrolysis and transglycosylation at α-1, 4- and α-1, 6-glucosidic linkages through one active center. We found a unique macromolecule recognition by the enzyme. A mixture of amylose and amylopectin from various sources was used as the substrate. Neopullulanase completely hydrolyzedamylose to maltose and a small amount of glucose, but scarcely hydrolyzed amylopectin. Although the molecular mass of potato amylopectin (approximately 108 Da) decreased slightly, the degradation of amylopectincompletely halted at the molecular mass of approximately 107Da. This difference in action on two macromolecules was also found in cyclomaltodextrinase and maltogenic amylase from Bacillus licheniformis.
ABSTRACT The specificity of Bacillus stearothermophilus TRS40 neopullulanase toward amylose and amylopectin was analyzed. Although this neopullulanase completely hydrolyzed amylose to produce maltose as the main product, it scarcely hydrolyzed amylopectin. The molecular mass of amylopectin was decreased by only one order of magnitude, from approximately 10 8 to 10 7 Da. Furthermore, this neopullulanase selectively hydrolyzed amylose when starch was used as a substrate. This phenomenon, efficient hydrolysis of amylose but not amylopectin, was also observed with cyclomaltodextrinase from alkaliphilic Bacillus sp. strain A2-5a and maltogenic amylase from Bacillus licheniformis ATCC 27811. These three enzymes hydrolyzed cyclomaltodextrins and amylose much faster than pullulan. Other amylolytic enzymes, such as bacterial saccharifying α-amylase, bacterial liquefying α-amylase, β-amylase, and neopullulanase from Bacillus megaterium , did not exhibit this distinct substrate specificity at all, i.e., the preference of amylose to amylopectin.
Cellulase inhibitors were synthesized from cellooligosaccharides and 1-deoxynojirimycin (DNJ) by transglycosylation, using a commercial cellulase. The structures of these cellulase inhibitors were proved to be 4-O-β-cellobiosyl-DNJ, 4-O-β-D-glucopyranosyl-DNJ and 6-O-β-cellobiosyl-DNJ by the results of 13C- and 1H-NMR analyses. The inhibitory activity of each inhibitor was investigated against several carboxymethylcellulases.
Transglucosylation from sucrose to acetic acid by sucrose phosphorylase (EC 2.4.1.7) was studied. 1-O-Acetyl-α-d-glucopyranose was isolated as the main product of the enzyme reaction. We also compared the pH-dependence of transglycosylation catalyzed by sucrose phosphorylase toward carboxyl and hydroxyl groups. With hydroquinone as an acceptor molecule, the transfer ratio of glucose residue was higher at neutral pH. This pH-activity profile was similar to that of the phosphorolysis of sucrose by sucrose phosphorylase, but with acetic acid as an acceptor molecule, the transfer ratio of glucose residue was higher at low pH. These findings suggest that the undissociated carboxyl group is essential to the acceptor molecule for the transglycosylation reaction of sucrose phosphorylase. In a sensory test, the sour taste of acetic acid was markedly reduced by glucosylation. The threshold value of the sour taste of acetic acid glucosides was approximately 100 times greater than that of acetic acid.
