Gluten-starch interactions in wheat gluten during carboxylic acid deamidation upon hydrothermal treatment.

After carboxylic acid deamidation upon heating (CADH), wheat gluten still contains a total of ∼10% insoluble fractions, of which ∼10% is starch, which depreciate the values of wheat gluten. To elucidate gluten-starch interactions and their role in the deamidation behavior of gluten, the macrostructural characteristics of gluten citric acid suspensions of different concentrations (1% and 10%, w/v) and with different types of residual starch chains (achieved by enzyme hydrolyzed by α-amylase and/or glucoamylase assisted by sonication) were investigated. We found the degradation of long starch chains and branched short chains induced dramatic bond-cleavages in insoluble glutenins and gliadins.

Properties and applications of starch modifying enzymes for use in the baking industry.

Enzyme technology has many potential applications in the baking industry because carbohydrate-active enzymes specifically react with carbohydrate components, such as starch, in complex food systems. Amylolytic enzymes are added to starch-based foods, such as baking products, to retain moisture more efficiently and to increase softness, freshness, and shelf life. The major reactions used to modify the structure of food starch include: (1) hydrolysis of α-1, 4 or α-1, 6 glycosidic linkages, (2) disproportionation by the transfer of glucan moieties, and (3) branching by formation of α-1, 6 glycosidic linkage.

Characterization and thermal inactivation kinetics of highly thermostable ramie leaf β-amylase.

We characterized ramie leaf β-amylase, and determined its thermostability and kinetic parameters. The enzyme was purified 53-fold using ammonium sulfate fractionation (40-60% saturation), anion exchange chromatography on DEAE-cellulose and gel permeation chromatography on Superdex-200. The purified enzyme was identified as β-amylase with molecular mass of 42kD.

Microbiota associated with the starter cultures and brewing process of traditional glutinous rice wine.

glutinous rice wine (produced mainly in Fujian province, China) is a traditional alcoholic beverage, which is prepared by fermenting cooked rice using a starter containing . In this review, the microbial diversity of fermentation starters from Fujian province, including fungi, bacteria, and yeast, is analyzed in comparison with those of "" (a traditional starter for making alcoholic beverages in Korea). The bacterial organization of Hong Qu starters was vastly variable in species composition and dominated by sp.

Novel formulation of low-fat spread using rice starch modified by 4-α-glucanotransferase.

Low-fat spreads were developed using a thermoreversible gelling agent, the 4-α-glucanotransferase (4αGT)-modified rice starch. The low-fat spreads consisted of the modified starch paste (or rice starch or maltodextrin), olive oil (0-30% w/w), egg yolk, salt, xanthan gum, and butter flavor, and were produced by homogenization, ultrasonic processing at 50% amplitude for 2min, and cold-gel setting at 4°C for 24h. Formulations with 15% and 20% of the modified starch paste resulted in highly stable oil-in-water low-fat spreads having varied textural properties and acceptable spreadability, whereas formulations with rice starch and maltodextrin did not yield enough stability and consistency.

Properties of a glycogen like polysaccharide produced by a mutant of Escherichia coli lacking glycogen synthase and maltodextrin phosphorylase.

Escherichia coli mutant TBP38 lacks glycogen synthase (GlgA) and maltodextrin phosphorylase (MalP). When grown on maltose in fed-batch fermentation TBP38 accumulated more than 50-fold higher glycogen-type polysaccharide than its parental strain. The polysaccharides were extracted at different growth stages and migrated as one peak in size-exclusion chromatography.

A continuous coupled spectrophotometric assay for debranching enzyme activity using reducing end-specific α-glucosidase.

A novel continuous spectrophotometric assay to measure the activity of the debranching enzyme and α-amylase has been developed. The assay mixture comprises the debranching enzyme (GlgX from Escherichia coli) or α-amylase (PPA from porcine pancreas), a reducing end-specific α-glucosidase (MalZ), maltodextrin-branched β-cyclodextrin (Glcn-β-CD) as the substrate, and the glucose oxidase/peroxidase system (GOPOD). Due to its high reducing end specificity, the branch chains of the substrates are not hydrolyzed by MalZ.

Novel characteristics of a carbohydrate-binding module 20 from hyperthermophilic bacterium.

In this study, a gene fragment coding carbohydrate-binding module 20 (CBM20) in the amylopullulanase (APU) gene was cloned from the hyperthermophilic bacteria Thermoanaerobacter pseudoethanolicus 39E and expressed in Escherichia coli. The protein, hereafter Tp39E, possesses very low sequence similarity with the CBM20s previously reported and has no starch binding site 2. Tp39E did not demonstrate thermal denaturation at 50 °C; however, thermal unfolding of the protein was observed at 59.

Introducing transglycosylation activity in Bacillus licheniformis α-amylase by replacement of His235 with Glu.

To understand the role of His and Glu in the catalytic activity of Bacillus licheniformis α-amylase (BLA), His235 was replaced with Glu. The mutant enzyme, H235E, was characterized in terms of its mode of action using labeled and unlabeled maltooctaose (Glc8). H235E predominantly produced maltotridecaose (Glc13) from Glc8, exhibiting high substrate transglycosylation activity, with Km=0.

Reaction kinetics of substrate transglycosylation catalyzed by TreX of Sulfolobus solfataricus and effects on glycogen breakdown.

We studied the activity of a debranching enzyme (TreX) from Sulfolobus solfataricus on glycogen-mimic substrates, branched maltotetraosyl-β-cyclodextrin (Glc₄-β-CD), and natural glycogen to better understand substrate transglycosylation and the effect thereof on glycogen debranching in microorganisms. The validation test of Glc₄-β-CD as a glycogen mimic substrate showed that it followed the breakdown process of the well-known yeast and rat liver extract. TreX catalyzed both hydrolysis of α-1,6-glycosidic linkages and transglycosylation at relatively high (>0.

Experimental evidence for a 9-binding subsite of Bacillus licheniformis thermostable α-amylase.

The action pattern of Bacillus licheniformis thermostable α-amylase (BLA) was analyzed using a series of (14)C-labeled and non-labeled maltooligosaccharides from maltose (G2) to maltododecaose (G12). Maltononaose (G9) was the preferred substrate, and yielded the smallest Km=0.36 mM, the highest kcat=12.

Physicochemical functionality of 4-α-glucanotransferase-treated rice flour in food application.

The physicochemical properties of 4-α-glucanotransferase (4αGTase)-modified rice flours were examined by measuring the molecular weight distribution, moisture sorption isotherm, and melting enthalpy of ice crystals. The results obtained by measuring the moisture sorption isotherm and melting enthalpy of ice crystals revealed that 4αGTase-modified rice flours had high water binding capacity than that of control rice flour. When the textural properties of noodles containing 4αGTase-treated rice flours after freeze-thaw cycling were measured by texture profile analysis, the textural properties of control noodle deteriorated.

Influence of environmental stresses on the stability of W/O/W emulsions containing enzymatically modified starch.

The present study was performed to investigate the stability of W/O/W emulsions containing 4-α-glucanotransferase (4αGTase)-treated starch against environmental stresses such as heating, shearing, and repeated freeze-thawing. W/O/W emulsions were subjected to thermal processing at different temperatures ranging from 30 to 90 °C for 30 min, constant shear for 0-7 min, and freeze-thaw cycling between -20 °C and 30 °C, respectively, and followed by encapsulation efficiency (EE) measurement. As for the case of thermal stress, it was clearly shown that addition of 4αGTase-treated starch in the internal aqueous phase of emulsions helped to maintain higher EE during thermal processing.

Characterization and application of an acidophilic and thermostable β-glucosidase from Thermofilum pendens.

The gene encoding a β-glucosidase from the archaeon Thermofilum pendens (Tpbgl) was cloned and expressed in Escherichia coli. The purified recombinant enzyme had a molecular mass of 77.8 kDa and released glucose or mannose from p-nitrophenyl-β-d-glucopyranoside (pNPG), cellobiose, mannobiose, and genistin.

An extremely thermostable amylopullulanase from Staphylothermus marinus displays both pullulan- and cyclodextrin-degrading activities.

A gene encoding an amylopullulanase of the glycosyl hydrolase (GH) family 57 from Staphylothermus marinus (SMApu) was heterologously expressed in Escherichia coli. SMApu consisted of 639 amino acids with a molecular mass of 75.3 kDa.

A novel domain arrangement in a monomeric cyclodextrin-hydrolyzing enzyme from the hyperthermophile Pyrococcus furiosus.

PFTA (Pyrococcus furiosus thermostable amylase) is a hyperthermophilic amylase isolated from the archaeon Pyrococcus furiosus. This enzyme possesses characteristics of both α-amylase- and cyclodextrin (CD)-hydrolyzing enzymes, allowing it to degrade pullulan, CD and acarbose-activities that are absent in most α-amylases-without the transferring activity that is common in CD-hydrolyzing enzymes. The crystal structure of PFTA revealed a unique monomeric subunit with an extended N-terminal region and an N'-domain folded into its own active site-a significantly altered domain configuration relative to that of the conventional dimeric CD-hydrolyzing amylases in glycoside hydrolase family 13.

Complete genome sequence of the hyperthermophilic archaeon Thermococcus sp. strain CL1, isolated from a Paralvinella sp. polychaete worm collected from a hydrothermal vent.

Thermococcus sp. strain CL1 is a hyperthermophilic, anaerobic, and heterotrophic archaeon isolated from a Paralvinella sp. polychaete worm living on an active deep-sea hydrothermal sulfide chimney on the Cleft Segment of the Juan de Fuca Ridge.

Acute effect of high-dose isoflavones from Pueraria lobata (Willd.) Ohwi on lipid and bone metabolism in ovariectomized mice.

We investigated the acute metabolic effects of isoflavones from Pueraria lobata (Willd.) Ohwi (IPL) in ovariectomized (OVX) mice. After 4 weeks of IPL feeding at 500 mg/day/kg body weight (OVX500), plasma 17β-estradiol concentrations were significantly higher (+25%, p < 0.

AMP-activated protein kinase β-subunit requires internal motion for optimal carbohydrate binding.

AMP-activated protein kinase interacts with oligosaccharides and glycogen through the carbohydrate-binding module (CBM) containing the β-subunit, for which there are two isoforms (β(1) and β(2)). Muscle-specific β(2)-CBM, either as an isolated domain or in the intact enzyme, binds carbohydrates more tightly than the ubiquitous β(1)-CBM. Although residues that contact carbohydrate are strictly conserved, an additional threonine in a loop of β(2)-CBM is concurrent with an increase in flexibility in β(2)-CBM, which may account for the affinity differences between the two isoforms.

Association of novel domain in active site of archaic hyperthermophilic maltogenic amylase from Staphylothermus marinus.

Staphylothermus marinus maltogenic amylase (SMMA) is a novel extreme thermophile maltogenic amylase with an optimal temperature of 100 °C, which hydrolyzes α-(1-4)-glycosyl linkages in cyclodextrins and in linear malto-oligosaccharides. This enzyme has a long N-terminal extension that is conserved among archaic hyperthermophilic amylases but is not found in other hydrolyzing enzymes from the glycoside hydrolase 13 family. The SMMA crystal structure revealed that the N-terminal extension forms an N' domain that is similar to carbohydrate-binding module 48, with the strand-loop-strand region forming a part of the substrate binding pocket with several aromatic residues, including Phe-95, Phe-96, and Tyr-99.

Restoration of autophagy by puerarin in ethanol-treated hepatocytes via the activation of AMP-activated protein kinase.

We investigated the effects of puerarin, the major isoflavone in Kudzu roots, on the regulation of autophagy in ethanol-treated hepatocytes. Incubation in ethanol (100 mM) for 24 h reduced cell viability by 20% and increased the cellular concentrations of cholesterol and triglycerides by 40% and 20%, respectively. Puerarin stimulation significantly recovered cell viability and reduced cellular lipid accumulation to a level comparable to that in untreated control cells.

Effects of enzymatically modified starch on the encapsulation efficiency and stability of water-in-oil-in-water emulsions.

The present study was performed to investigate the possibility of using 4-α-glucanotransferase (4αGTase)-treated starch in W/O/W emulsions to increase their encapsulation efficiency (EE) and stability. Emulsions were prepared using soybean oil, polyglycerol polyricinoleate (PGPR), 4αGTase-treated starch and Tween 20. The mean diameter of W/O/W droplets ranged from 4 to 10μm depending on the sonication time.

Overexpression and characterization of a novel transgalactosylic and hydrolytic β-galactosidase from a human isolate Bifidobacterium breve B24.

After the complete gene of a β-galactosidase from human isolate Bifidobacterium breve B24 was isolated by PCR and overexpressed in E. coli, the recombinant β-galactosidase was purified to homogeneity and characterized for the glycoside transferase (GT) and glycoside hydrolase (GH) activities on lactose. One complete ORF encoding 691 amino acids (2,076 bp) was the structural gene, LacA (galA) of the β-gal gene.

Role of maltose enzymes in glycogen synthesis by Escherichia coli.

Mutants with deletion mutations in the glg and mal gene clusters of Escherichia coli MC4100 were used to gain insight into glycogen and maltodextrin metabolism. Glycogen content, molecular mass, and branch chain distribution were analyzed in the wild type and in ΔmalP (encoding maltodextrin phosphorylase), ΔmalQ (encoding amylomaltase), ΔglgA (encoding glycogen synthase), and ΔglgA ΔmalP derivatives. The wild type showed increasing amounts of glycogen when grown on glucose, maltose, or maltodextrin.

Screening wild yeast strains for alcohol fermentation from various fruits.

Wild yeasts on the surface of various fruits including grapes were surveyed to obtain yeast strains suitable for fermenting a novel wine with higher alcohol content and supplemented with rice starch. We considered selected characteristics, such as tolerance to alcohol and osmotic pressure, capability of utilizing maltose, and starch hydrolysis. Among 637 putative yeast isolates, 115 strains exhibiting better growth in yeast-peptone-dextrose broth containing 30% dextrose, 7% alcohol, or 2% maltose were selected, as well as five α-amylase producers.