Search results for "Maltose"
showing 10 items of 41 documents
Synthesis of Isomaltooligosaccharides by Saccharomyces cerevisiae Cells Expressing Aspergillus niger α‑Glucosidase
2017
The α-glucosidase encoded by the aglA gene of Aspergillus niger is a secreted enzyme belonging to family 31 of glycoside hydrolases. This enzyme has a retaining mechanism of action and displays transglycosylating activity that makes it amenable to be used for the synthesis of isomaltooligosaccharides (IMOs). We have expressed the aglA gene in Saccharomyces cerevisiae under control of a galactose-inducible promoter. Recombinant yeast cells expressing the aglA gene produced extracellular α-glucosidase activity about half of which appeared cell bound whereas the other half was released into the culture medium. With maltose as the substrate, panose is the main transglycosylation product after 8…
Transmembrane signaling and cytoplasmic signal conversion by dimeric transmembrane helix 2 and a linker domain of the DcuS sensor kinase
2020
Transmembrane (TM) signaling is a key process of membrane-bound sensor kinases. The C4-dicarboxylate (fumarate) responsive sensor kinase DcuS of Escherichia coli is anchored by TM helices TM1 and TM2 in the membrane. Signal transmission across the membrane relies on the piston-type movement of the periplasmic part of TM2. To define the role of TM2 in TM signaling, we use oxidative Cys cross-linking to demonstrate that TM2 extends over the full distance of the membrane and forms a stable TM homodimer in both the inactive and fumarate-activated state of DcuS. An S186xxxGxxxG194 motif is required for the stability and function of the TM2 homodimer. The TM2 helix further extends on the periplas…
Bioequivalence decision for nanoparticular iron complex drugs for parenteral administration based on their disposition
2017
Although parenteral iron products have been established to medicinal use decades before, their structure and pharmacokinetic properties are not fully characterized yet. With its' second reflection paper on intravenous iron-based nano-colloidal products (EMA/CHMP/SWP/620008/2012) the European Medicine Agency provided an extensive catalogue of methods for quality, non-clinical and pharmacokinetic studies for the comparison of nano-sized iron products to an originator (EMA, 2015). For iron distribution studies, the reflection paper assumed the use of rodents. In our tests, we used a turkey fetus model to investigate time dependent tissue concentrations in pharmacological and toxicological rele…
GH57 amylopullulanase from Desulfurococcus amylolyticus JCM 9188 can make highly branched cyclodextrin via its transglycosylation activity.
2018
Abstract Desulfurococcus amylolyticus is an anaerobic and hyperthermophilic crenarchaeon that can use various carbohydrates as energy sources. We found a gene encoding a glycoside hydrolase family 57 amylolytic enzymes (DApu) in a putative carbohydrate utilization gene cluster in the genome of D. amylolyticus . This gene has an open reading frame of 1,878 bp and consists of 626 amino acids with a molecular mass of 71 kDa. Recombinant DApu (rDApu) completely hydrolyzed pullulan to maltotriose by attacking α-1,6-glycosidic linkages, and was able to produce glucose and maltose from soluble starch and amylopectin. Although rDApu showed no activity toward α-cyclodextrin (CD) and β-CD, maltooctao…
Bioprotection Can Be Tuned with Proper Protein/Saccharide Ratio: The Case of Solid Amorphous Matrices
2018
Saccharides, and in particular trehalose, are well known for their high efficiency in protecting biostructures against adverse environmental conditions. The protein dynamics is known to be highly inhibited in a low-water trehalose host medium, the inhibition being markedly dependent on the amount of residual water. Besides hydration, the protein/sugar ratio is expected to affect the properties of saccharide amorphous matrices. In this work, we report an infrared spectroscopy study in dry amorphous matrices of various sugars (the disaccharides trehalose, maltose, sucrose, and lactose, and the trisaccharide raffinose) containing myoglobin, at different protein/sugar ratios. We analyze the str…
Acetobacter musti sp. nov., isolated from Bobal grape must
2016
An acetic acid bacterium (strain Bo7T), obtained during a study of the microbial diversity of spontaneous fermentations of Bobal grape must, was subjected to a taxonomic study using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences allocated strain Bo7T to the genus Acetobacter, and revealed Acetobacter aceti and Acetobacter oeni to be nearest neighbours (99.57 % 16S rRNA gene sequence similarity between strain Bo7T and A. oeni CECT 5830T, and 98.76 % between strain Bo7T and A. aceti CECT 298T). Cells of strain Bo7T are Gram-negative, motile rods, catalase-positive and oxidase-negative. The DNA G+C content of strain Bo7T was 58.0 mol%. DNA–DNA hybridizations demo…
Chewing bread: impact on alpha-amylase secretion and oral digestion
2017
During chewing, saliva helps in preparing food bolus by agglomerating formed particles and initiates food enzymatic breakdown. However, limited information is actually available on the adaptation of saliva composition during oral processing of complex foods, especially for foods that are sensitive to salivary enzymes. We addressed this question in the context of starch–based products and salivary alpha-amylase. The objectives were two-fold: 1) determining if salivary alpha-amylase secretion can be modulated by bread type and 2) evaluating the contribution of the oral phase in bread enzymatic breakdown.Mouthfuls of three different wheat breads (industrial, artisan and whole breads) were chew…
Influence of nitrogen and carbon sources on the production of ochratoxin A by ochratoxigenic strains of Aspergillus spp. isolated from grapes.
2008
This work studies the influence of nitrogen and carbon source on ochratoxin A production by three Aspergillus isolates A. ochraceus (Aso2), A. carbonarius (Ac25) and A. tubingensis (Bo66), all isolated from grapes. A basal medium (0.01 g/l FeSO4.7H2O, 0.5 g/l MgSO4.7H2O, 0.5 g/l Na2HPO4.2H2O, 1.0 g/l KCl) was prepared. This medium was supplemented with different nitrogen sources, both inorganic [(NH4)3PO(4), 0.3 g/l plus NH4NO3, 0.2 g/l] and organic (histidine, proline, arginine, phenylalanine, tryptophan or tyrosine) at two concentrations (0.05 g/l or 0.3 g/l), and different carbon sources (sucrose, glucose, maltose, arabinose or fructose) at three concentrations (10 g/l, 50 g/l or 150 g/l…
Influence of the Liquefied Starch Composition and pH on the Saccharification at the Obtaining of Maltose Syrup
1970
In this paper the influence of the composition of the liquefied starch and of pH on the quality of saccharification at the obtaining of maltose syrup is investigated. A large number of experiments (68) in various liquefaction conditions show that Dextrose Equivalent (DE) and the composition in hydrolysis products with Degree of Polymerisation higher as four (DP ≥4) in the liquefied starch have a strong influence on the saccharification products, mainly on the maltose content in the maltose syrups. The liquefied starch with DE lower as 25 has smaller amounts of DP ≥4 (40 to 60%), whereas the liquefied starch with DE between 25 and 27 has high amounts of DP ≥4 (60 to 80%). For the production …
Modelling of Starch Gelatinisation and Liquefaction with the Enzyme Liquozyme
2011
In this paper the influence of the enzyme Liquozyme Supra concentration (0.4-1.2 kg/t dry substance DS) and gelatinisation time (3-11 min.) on the liquefied starch quality is investigated. The composition in sugars with different Degrees of Polymerisation (DP) as DP1 (glucose), DP2 (maltose), DP3 (maltotriose), DP4 (maltotetrose) and oligosaccharides with DP≥5 is analysed by using HPLC with RI detector. The products obtained have different DP, the main components being oligosaccharides with DP≥5, followed by small amount of DP3+DP4 and much smaller concentrations of DP1; no DP2 is produced by this enzyme. Two quality criteria: the percent of oligosaccharides with DP≥5 and the percent of DP1…