Understanding Antidiabetic Potential of Oligosaccharides from Red Alga Dulse Xylan by Investigating α-Amylase and α-Glucosidase Inhibition.

In this study, the α-glucosidase (maltase-glucoamylase: MGAM) and α-amylase inhibitory properties elicited by xylooligosaccharides (XOSs) prepared from dulse xylan were analysed as a potential mechanism to control postprandial hyperglycaemia for type-2 diabetes prevention and treatment. Xylan was purified from red alga dulse powder and used for enzymatic hydrolysis using Sucrase X to produce XOSs. Fractionation of XOSs produced xylobiose (X2), β-(1→3)-xylosyl xylobiose (DX3), xylotriose (X3), β-(1→3)-xylosyl-xylotriose (DX4), and a dulse XOS mixture with ≥ 4 xylose units (DXM).

Enhanced overexpression of secreted enzymes by discrete repeat promoters in Streptomyces lividans.

Streptomyces lividans is an efficient host for extracellular overproduction of recombinant proteins. To enhance the overexpression strength of S. lividans, we designed several kinds of expression plasmids with different positioning of repeat promoters.

Construction and development of a novel dual-gene coexpression system to promote heterologous protein secretion for Streptomyces.

Streptomyces lividans is a potent host for the extracellular overproduction of heterologous proteins. To further improve the usability and productivity of S. lividans, a dual gene expression vector of "pTSKr duet" containing two strong constitutive promoters, scmpPc and kasOp*, was constructed.

Isolation of the hemeoxygenase-1 inducer from rice-derived peptide.

Bioactive peptides with various health benefits have been reported from rice protein hydrolysates. We previously showed that rice-derived peptides (RP) increased intracellular glutathione levels and induced the expression of γ-glutamylcysteine synthetase, which is regulated by nuclear transcription factor-erythroid 2-related factor 2 (Nrf2). Heme oxygenase-1 (HO-1) is an important Nrf2 downstream antioxidant enzyme that protects against oxidative stress.

Improvement in hyperexpression with a combination of truncated scmp promoter and Streptomyces lividans.

We have previously reported a powerful promoter from the Streptomyces cinnamoneus TH-2 strain named "scmp" and created an expression vector of pTONA5a for expression using S. lividans. The full-length scmp promoter sequence consists of 424 bp upstream of a metalloendoprotease gene in the S.

Molecular investigation of proanthocyanidin from Alpinia zerumbet against the influenza A virus.

Proanthocyanidins (PACs) have various bioactivities, such as being anti-bacterial, anti-cancer, and anti-oxidant. Consequently, they have been vigorously studied for the development of new natural bioactive compounds. Recently, PAC was isolated from leaves and pseudostems of the medicinal plant Alpinia zerumbet (Pers.

Preparation of β(1→3)/β(1→4) xylooligosaccharides from red alga dulse by two xylanases from Streptomyces thermogriseus.

Red alga dulse contains xylan with β(1→3)/β(1→4) linkages. We previously prepared xylooligosaccharides (XOSs) from dulse xylan; however, the product contained many D-xylose residues and fewer XOSs with β(1→3) linkages. To improve the efficiency of XOS production, we prepared two recombinant endoxylanases from Streptomyces thermogriseus (StXyl10 and StXyl11).

Identification of an anti-plant-virus molecule in Alpinia zerumbet.

In plants, viral diseases are second only to fungal diseases in terms of occurrence, and cause substantial damage to agricultural crops. The aqueous extracts of shell ginger, Alpinia zerumbet exhibit inhibitory effects against virus infections in belonging to the Solanaceae family. In this study, we isolated an anti-plant-virus molecule from the extracts using a conventional method involving a combination of reversed phase column chromatography, dialysis, and lyophilization.

Hepatoprotective Activity of Yellow Chinese Chive against Acetaminophen-Induced Acute Liver Injury via Nrf2 Signaling Pathway.

Glutathione, the most abundant intracellular antioxidant, protects cells against reactive oxygen species induced oxidative stress and regulates intracellular redox status. We previously demonstrated that yellow Chinese chive (ki-nira) increased the intracellular glutathione levels. Acetaminophen (APAP) is a commonly used analgesic.

Protective Effects of Rice Peptide Oryza Peptide-P60 against Oxidative Injury through Activation of Nrf2 Signaling Pathway and .

We previously showed that commercially available rice peptide Oryza Peptide-P60 (OP60) increased the intracellular glutathione levels. This study aimed to evaluate the antioxidant potential of this peptide and assess its mechanism of action. Pretreatment of HepG2 cells with OP60 reduced the cytotoxicity caused by HO or acetaminophen (APAP) (47.

Molecular insights into the mechanism of substrate recognition of transglutaminases.

The microbial TGase from has used in various food industries. However, the detailed substrate specificities of TGases from the species toward the natural peptides remains to be unclear. In this study, we conducted the comparison of two different TGases from (SMTG) and (SCTG).

Enzymatic Degradation of Allergen Peptides from Bovine Casein by a Combination of Streptomyces Aminopeptidases.

Cow's milk is one of the most common allergenic foods. Cow's milk allergy is mainly an IgE-mediated hypersensitivity reaction, and the major allergens from cow's milk have been found to be caseins, β-lactoglobulin, and α-lactalbumin. Several peptides derived from bovine casein are known allergens in cow's milk.

Active site pocket of Streptomycesd-stereospecific amidohydrolase has functional roles in aminolysis activity.

d-Stereospecific amidohydrolase from Streptomyces sp. 82F2 (DAH) recognizes d-amino acyl ester derivatives as substrates and catalyzes hydrolysis and aminolysis to yield d-amino acids and d-amino acyl peptides or amide derivatives, respectively. Crystallographic analysis has revealed that DAH possesses a large cavity with a small pocket at the bottom.

Sake lees hydrolysate protects against acetaminophen-induced hepatotoxicity via activation of the Nrf2 antioxidant pathway.

Acetaminophen is a commonly used analgesic. However, an overdose of acetaminophen causes severe hepatotoxicity via depletion of hepatic glutathione. Here, we investigated the protective effects of sake lees hydrolysate against acetaminophen-induced hepatotoxicity in mice.

Anti-oxidative Activity of Hydrolysate from Rice Bran Protein in HepG2 Cells.

Glutathione (GSH) is an ubiquitous thiol-containing tripeptide, which plays important roles in cellular protection from oxidative stress. In our search for a dietary source that can increase GSH levels, we discovered that a 24 h treatment of HepG2 cells with rice bran protein hydrolysate (RBPH), prepared by Umamizyme G-catalyzed hydrolysis, increased the GSH content in a dose-dependent manner. RBPH elevated the expression levels of γ-glutamylcysteine synthetase (γ-GCS), which constitutes the rate-limiting enzyme of GSH synthesis, and of another two enzymes, hemeoxygenase-1 (HO-1) and reduced nicotinamide adenine dinucleotide (phosphate): quinone oxidoreductase 1 (NQO1).

Hepatoprotective effects of rice-derived peptides against acetaminophen-induced damage in mice.

Glutathione, the most abundant intracellular antioxidant, protects cells against reactive oxygen species induced oxidative stress and regulates intracellular redox status. We found that rice peptides increased intracellular glutathione levels in human hepatoblastoma HepG2 cells. Acetaminophen is a commonly used analgesic.

Pronounced effect of hapten binding on thermal stability of an anti-(4-hydroxy-3-nitrophenyl)acetyl antibody possessing a glycine residue at position 95 of the heavy chain.

Immune response to T-cell-dependent antigens is highly dynamic; several B-cell clones responsible for antibody production appear alternately during immunization. It was previously shown that at least two-types of antibodies are secreted after immunization with (4-hydroxy-3-nitrophenyl)acetyl (NP); one has Tyr and another has Gly at position 95 of the heavy chain (referred to as Tyr95- and Gly95-type). The former appeared at an early stage, while the latter appeared at a late stage, i.

Somatic hypermutation of immunoglobulin genes in Rad18 knockout mice.

Somatic hypermutation (SHM) of immunoglobulin (Ig) genes is triggered by the activity of activation-induced cytidine deaminase (AID). AID induces DNA lesions in variable regions of Ig genes, and error-prone DNA repair mechanisms initiated in response to these lesions introduce the mutations that characterize SHM. Error-prone DNA repair in SHM is proposed to be mediated by low-fidelity DNA polymerases such as those that mediate trans-lesion synthesis (TLS); however, the mechanism by which these enzymes are recruited to AID-induced lesions remains unclear.

Molecular insights into the mechanism of thermal stability of actinomycete mannanase.

Streptomyces thermolilacinus mannanase (StMan), which requires Ca(2+) for its enhanced thermal stability and hydrolysis activity, possesses two Ca(2+) -binding sites in loop6 and loop7. We evaluated the function of the Ca(2+) -binding site in loop7 and the hydrogen bond between residues Ser247 in loop6 and Asp279 in loop7. The Ca(2+) -binding in loop7 was involved only in thermal stability.

Structural dynamics of a single-chain Fv antibody against (4-hydroxy-3-nitrophenyl)acetyl.

Protein structure dynamics are critical for understanding structure-function relationships. An antibody can recognize its antigen, and can evolve toward the immunogen to increase binding strength, in a process referred to as affinity maturation. In this study, a single-chain Fv (scFv) antibody against (4-hydroxy-3-nitrophenyl)acetyl, derived from affinity matured type, C6, was designed to comprise the variable regions of light and heavy chains connected by a (GGGGS)3 linker peptide.

Affinity maturation of anti-(4-hydroxy-3-nitrophenyl)acetyl antibodies accompanies a modulation of antigen specificity.

Anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibodies bearing λ1 chains are known to possess fine specificity, referred to as heterocliticity, which causes these antibodies to bind to hapten analogues such as (4-hydroxy-3-iodo-5-nitrophenyl)acetyl (NIP) and (4-hydroxy-3,5-dinitrophenyl)acetyl (NNP) with higher affinity than to the autologous hapten, NP. They also show preferential binding to the phenolate form of hapten than to the phenolic form. We address here the question of whether affinity maturation accompanies in the fine specificity of these antibodies by analyzing the interaction between NP1-, NIP1-, or NNP1-hen egg lysozyme and anti-NP antibodies that possess different association constants to NP using a surface plasmon resonance biosensor.

The loop structure of Actinomycete glycoside hydrolase family 5 mannanases governs substrate recognition.

Endo-β-1,4-mannanases from Streptomyces thermolilacinus (StMan) and Thermobifida fusca (TfMan) demonstrated different substrate specificities. StMan hydrolyzed galactosylmannooligosaccharide (GGM5; 6(III) ,6(IV) -α-d-galactosyl mannopentaose) to GGM3 and M2, whereas TfMan hydrolyzed GGM5 to GGM4 and M1. To determine the region involved in the substrate specificity, we constructed chimeric enzymes of StMan and TfMan and evaluated their substrate specificities.

Application of two newly identified and characterized feruloyl esterases from Streptomyces sp. in the enzymatic production of ferulic acid from agricultural biomass.

Ferulic acid (FA), a component of hemicellulose in plant cell walls, is a phenolic acid with several potential applications based on its antioxidant properties. Recent studies have shown that feruloyl esterase (FAE) is a key bacterial enzyme involved in FA production from agricultural biomass. In this study, we screened a library of 43 esterases from Streptomyces species and identified two enzymes, R18 and R43, that have FAE activity toward ethyl ferulate.

Overexpression of a novel Arabidopsis PP2C isoform, AtPP2CF1, enhances plant biomass production by increasing inflorescence stem growth.

In contrast to mammals, higher plants have evolved to express diverse protein phosphatase 2Cs (PP2Cs). Of all Arabidopsis thaliana PP2Cs, members of PP2C subfamily A, including ABI1, have been shown to be key negative regulators of abscisic acid (ABA) signalling pathways, which regulate plant growth and development as well as tolerance to adverse environmental conditions. However, little is known about the enzymatic and signalling roles of other PP2C subfamilies.

Inhibitory effect of collagen-derived tripeptides on dipeptidylpeptidase-IV activity.

The collagen tripeptide fragments Gly-Ala-Hyp, Gly-Pro-Ala and Gly-Pro-Hyp were generated by hydrolyzing collagen from pig-skin, cattle-skin, fish-scales and chicken-feet, respectively, with Streptomyces collagenase. Collagenase treatment increased the concentration of tripeptides in the hydrolysates by 13-15% (w/w). Of the three peptides, Gly-Pro-Hyp was a true peptidic inhibitor of dipeptidylpeptidase-IV (DPP-IV), because DPP-IV could not hydrolyze the bond between Pro-Hyp.