Amelioration of abdominal obesity by low-molecular-weight polyphenol (Oligonol) from lychee

The effect of low-molecular-weight polyphenols extracted from lychee (Oligonol) on metabolic syndrome characterized by abdominal obesity was examined. We performed a clinical trial for Oligonol conducted by randomized double-blind, placebo-controlled study. Eighteen (male, 14; female, 4) adult volunteers with abdominal circumference over 85 cm were enrolled and divided into two groups, Oligonol and placebo groups. All subjects took two capsules of Oligonol (50 mg/capsule) or placebo twice a day for 10 weeks. Physical and haematological examinations as well as a CT scan of the abdomen were carried out, before (control) and 10 weeks after Oligonol intake. Clinical parameters of body weight, abdominal circumference and visceral fat volume were significantly decreased in the Oligonol group compared to the control. Insulin resistance was improved by Oligonol in conjunction with elevation of serum adiponectin. These results suggest that Oligonol ameliorates metabolic syndrome by reducing visceral fat obesity.     

Isolation and identification of xenobiotic aryl hydrocarbon receptor ligands in dyeing wastewater

Dyeing wastewater collected in Kyoto city, Japan, was investigated for the occurrence of aryl hydrocarbon receptor (AhR) ligands by using an AhR-responsive reporter gene assay. Concentrated extracts of wastewater samples elicited a dose-dependent increase in AhR ligand activity, and several hydrophobic HPLC fractions of the extracts were highly effective in inducing AhR ligand activity. Three potential AhR ligands were isolated from these fractions and identified to be Disperse Red 92, Disperse Yellow 64, and 3'-hydroxybenzo[b]quinophthalone by using HPLC and LC-MS/MS. Disperse Red 92, which has also been detected in the treated effluent from a sewage plant receiving the wastewater, is an anthraquinone disperse dye showing weak AhR binding affinity in the assay. Disperse Yellow 64 and 3'-hydroxybenzo[b]quinophthalone are quinoline disperse dyes capable of activating the AhR at nanomolar concentrations. In particular, Disperse Yellow 64 is a highly potent AhR ligand that was 3 times more effective in inducing AhR ligand activity than beta-naphthoflavone in the assay. Quinoline disperse dyes are suggested to be a new class of xenobiotic AhR ligands which pose a danger to aquatic biota and human health.     

Burning velocities and kinetics of H2/NF3/N2, CH4/NF3/N2, and C3H8/NF3/N2 flames

The combustion characteristics and reaction mechanism of mixtures containing nitrogen trifluoride (NF₃) were investigated. Burning velocities for H₂/NF₃/N₂, CH₄/NF₃/N₂, and C₃H₈/NF₃/N₂ flames were determined for the first time at various equivalence ratios and N₂ mole fractions. The burning velocities of the latter two flames were similar and showed peaks at equivalence ratios of ∼1.0, while those of the H₂/NF₃/N₂ flames had the pronounced peak at low equivalence ratios where the formation of the wrinkled flames was observed. A detailed kinetic model was constructed to simulate the laminar burning velocities of H₂/NF₃/N₂ and CH₄/NF₃/N₂ flames. The model accurately reproduced the experimental results. Analyses of the reaction mechanism revealed the major reaction pathways that involve the decomposition of NF₃, the oxidation and chain-fluoridation of H₂ and CH₄, and the formation of N₂.     

Histidine 210 mutant of a trypsin-type Achromobacter protease I shows broad optimum pH range

Achromobacter protease I (API), a lysine-specific serine protease, shows one order of magnitude higher activity than bovine trypsin, while its optimum pH is in the alkaline region at about pH 9. To improve the optimum pH range, mutant enzyme His 210 replaced by Ser(H210S), Ala (H210A), and Lys (H210K) were constructed. The optimum pH of H210S shifted from about pH 9 (wild-type enzyme) to about pH 7, retaining its high activity. The putative electrostatic interaction between His 210 and catalytic Asp 113 was elucidated by the optimum-pH shift of H210K and H210A. These results indicate that this unconserved His 210 in API, which plays a key role in generating the useful peptidase, broadened the optimum-pH range without decreasing lysylendo-peptidase activity.     

Diamines prevent thermal aggregation and inactivation of lysozyme

Protein aggregation is a major obstacle in both biological applications and biomedical fields involving proteins. In this study, we investigated the essential structure of small additives that function as chemical chaperones. Aggregation-suppressing competent additives were 1,3-diaminopropane, 1,4-diaminobutane, and 1,5-diaminopentane, which suppressed aggregation in the given order; whereas no diols or monoamines prevented the thermal aggregation and the inactivation of lysozyme. The heat-inactivation rate of lysozyme with 1,3-diaminopropane was almost identical to that of lysozyme with spermine and arginine ethylester, which are the most prominent additives reported yet.     

Engineering of novel tamavidin 2 muteins with lowered isoelectric points and lowered non-specific binding properties

The avidin-biotin interaction is widely employed as a universal tool in numerous biotechnological applications. In avidin-biotin technology, non-specific binding to biological macromolecules is a hindrance. The major origin of this non-specific binding is the electrical charge of the surface of biotin-binding proteins. Tamavidin 2, a fungal avidin-like protein that binds biotin with an extremely high affinity, can be produced as a soluble recombinant protein in Escherichia coli. The isoelectric point of tamavidin 2 is 7.4-7.5, lower than avidin (10.0), and slightly higher than that of streptavidin (6.0-7.5). Here, we genetically engineered charge mutants of tamavidin 2 to reduce non-specific binding. By substituting an acidic residue (glutamic acid) for basic residues (arginine and lysine), we constructed three mutant proteins (muteins) and confirmed their high-level production in soluble form in E. coli, as well as that of tamavidin 2.?We then tested these proteins for non-specific binding to salmon sperm DNA, glycoproteins (integrin and fibronectin), and IgG from human sera. The muteins showed lower non-specific binding than tamavidin 2 to these macromolecules. In particular, one mutein, tamavidin-R104EK141E, which had the lowest isoelectric point (5.8-6.2) among avidin, streptavidin and tamavidin 2, displayed the lowest non-specific binding. The affinity of this mutein to biotin was high, comparable with that of tamavidin 2. These findings indicate that tamavidin-R104EK141E has the potential to serve as a robust tool in the numerous applications of biotin-binding proteins.     

The effect of osmotic dehydrofreezing on the role of the cell membrane in carrot texture softening after freeze-thawing

To understand the protective mechanism of the osmotic dehydrofreezing technique on carrot texture after freeze-thawing, two mechanical texture parameters, fracture stress related to the cell wall and initial modulus related to the cell membrane, as well as cell membrane water permeability using PFG-NMR were evaluated. In particular, to understand the role of the cell membrane in texture alteration, tissue in which the cell membrane was exposed to chloroform vapor was used. Although dehydrofreezing protected texture from freezing damage, the effect was only observed with respect to fracture stress, with exhibited values close to those for raw tissue. However, there was no protective effect on initial modulus and water permeability, in which values did not differ from those of cell membrane-free tissue. More specifically, osmotic dehydrofreezing had no effect on the cell membrane induced by freeze-thawing.