Identification and characterization of a novel thermo-stable endo-ß-N-acetylglucosaminidase from Rhizomucorpusillus.

Endo-ß-N-acetylglucosaminidase (ENGase) is an enzyme that hydrolyzes the chitobiose core of N-glycans and is widely used for glycan analysis on glycoproteins and preparation of precursors for glycosylated compounds. While most of the ENGases that can hydrolyze complex-type glycans are derived from eukaryotes, their production by heterologous expression using Escherichia coli is insufficient, making the production process expensive. From an industrial perspective, there is a need for a less expensive enzyme with higher activity and stability. In this study, we identified a novel ENGase gene from a thermophilic fungus, Rhizomucor pusillus, and named it Endo-Rp. Characterization of the recombinant Endo-Rp showed that the enzyme had maximum hydrolytic activity at 60 °C and hydrolyzed high-mannose-type and biantennary complex-type glycans, but not (2,4)-branched triantennary complex-type or fucosylated glycans. Endo-Rp also hydrolyzed N-glycans attached to RNase B and human transferrin. In summary, we consider Endo-Rp to be a valuable enzyme in various scientific and industrial applications.

Syntheses and antimicrobial activities of ogipeptin derivatives.

Novel cyclic peptide derivatives based on ogipeptins A, B, C, and D were synthesized. Starting with a mixture of ogipeptins A-D, a practical four-step synthetic procedure was followed to prepare novel derivatives with various kinds of acyl side chains. Among the 45 new synthetic derivatives identified, the antibacterial activities of compounds 8-3 and 8-38 were comparable with those of ogipeptin A. In in vitro nephrotoxicity screening using LLC-PK1 cells, compounds 8-3 and 8-38 showed significantly lower cytotoxicity (LD20 > 480 µM) than colistin (LD20 = 44.2 µM).

Biosynthesis of nectrisine in Thelonectria discophora SANK 18292.

Nectrisine, an iminosugar with a heterocyclic nitrogen-containing 5-membered ring, acts as a glycosidase inhibitor. Thelonectria discophora SANK 18292, a fungus, was identified as a nectrisine producer from its microbial library in our screening for nectrisine producing microorganisms. Biosynthesis of nectrisine produced by the fungus was studied using stable isotope tracer techniques. Incorporation of (13)C-labeled d-ribose and d-xylose into nectrisine was confirmed by mass spectrometry and (13)C NMR spectroscopy, which suggested that these were its precursors. Chromatographic separation of the hot water extract from the culture broth afforded not only nectrisine, but also substantial amounts of 4-amino-4-deoxyarabinitol. Incubation of the latter with the crude enzyme of the fungus at room temp. caused an increase in levels of nectrisine together with a decrease in amounts of the administered potential precursor suggesting that it is a biosynthetic intermediate. From these results, a biosynthetic pathway to nectrisine is proposed via d-xylulose 5-phosphate and 4-amino-4-deoxyarabinitol by the pentose phosphate pathway.

Property development for biaxial drawing of ethylene-tetrafluoroehtylene copolymer films and resultant fractural behavior analyzed by in situ X-ray measurements.

The property development of the ethylene-tetrafluoroethylene copolymer (ETFE) membrane induced by simultaneous biaxial drawing was investigated. Commonly, tensile strength can be increased by drawing; conversely, tear resistance decreases. In this study, the balance between tensile strength and tear resistance for the resultant ETFE membrane was optimized achieved by a combination of lamination of low molecular weight (LMW) and high molecular weight (HMW) layers and subsequent biaxial drawing. The structural factor determining tear resistance of these biaxially drawn membranes was determined based on in situ small-angle X-ray scattering (SAXS) measurement during tensile deformation simulating tearing tests. Lozenge shaped scattering, which indicated inclined lamellae, was observed during such tensile deformation of the resultant membranes. Remarkably, this inclined lamellar structure was observed for the pure LMW membrane; however, it also appeared at the interface between LMW and HMW layers within biaxially drawn membranes. For the membrane exhibiting the highest tearing strength, the fraction of such inclined lamella increased up to the critical strain corresponding to the actual sample breaking. These results confirm that the inclined lamellar structure absorbed strain during membrane tearing.

Novel Nrf2 activators from microbial transformation products inhibit blood-retinal barrier permeability in rabbits.

BACKGROUND AND PURPOSE: Nuclear factor erythroid 2-related factor 2 (Nrf2) is a redox-sensitive transcription factor that binds to antioxidant response elements located in the promoter region of genes encoding many antioxidant enzymes and phase II detoxifying enzymes. Activation of the Nrf2 pathway seems protective for many organs, and although a well-known Nrf2 activator, bardoxolone methyl, was evaluated clinically for treating chronic kidney disease, it was found to induce adverse events. Many bardoxolone methyl derivatives, mostly derived by chemical modifications, have already been studied. However, we adopted a biotransformation technique to obtain a novel Nrf2 activator. EXPERIMENTAL APPROACH: The potent novel Nrf2 activator, RS9, was obtained from microbial transformation products. Its Nrf2 activity was evaluated by determining NADPH:quinone oxidoreductase-1 induction activity in Hepa1c1c7 cells. We also investigated the effects of RS9 on oxygen-induced retinopathy in rats and glycated albumin-induced blood-retinal barrier permeability in rabbits because many ocular diseases are associated with oxidative stress and inflammation. KEY RESULTS: Bardoxolone methyl doubled the specific activity of Nrf2 in Hepa1c1c7 cells at a much higher concentration than RS9. Moreover, the induction of Nrf2-targeted genes was observed at a one-tenth lower concentration of RS9. Interestingly, the cytotoxicity of RS9 was substantially reduced compared with bardoxolone methyl. Oral and intravitreal administration of RS9 ameliorated the pathological scores and leakage in the models of retinopathy in rats and ocular inflammation in rabbits respectively. CONCLUSION AND IMPLICATIONS: Nrf2 activators are applicable for treating ocular diseases and novel Nrf2 activators have potential as a unique method for prevention and treatment of retinovascular disease.

Haplofungins, novel inositol phosphorylceramide synthase inhibitors, from Lauriomyces bellulus SANK 26899 I. Taxonomy, fermentation, isolation and biological activities.

In the course of screening for antifungal agents, we have discovered eight novel compounds, haplofungin A, B, C, D, E, F, G and H, from a culture broth of the fungus strain Lauriomyces bellulus SANK 26899. Haplofungins are composed of an arabinonic acid moiety linked through an ester to a modified long alkyl chain and show potent inhibitory activities against fungal inositol phosphorylceramide (IPC) synthase. Haplofungin A inhibited the activity of IPC synthase from Saccharomyces cerevisiae with an IC(50) value of 0.0015 microg ml(-1). This inhibitor also suppressed the growth of Candida glabrata at the MIC value of 0.5 microg ml(-1).

Ascotricins A and B, novel antagonists of sphingosine-1-phosphate receptor 1 from Ascotricha chartarum Berk. SANK 14186.

Ascotricins A and B were isolated as novel sphingosine-1-phosphate receptor 1 (S1P(1)) antagonists from a cultured broth of a fungus identified as Ascotricha chartarum Berk. SANK 14186. The two compounds were purified by solvent extraction, reversed-phase (RP) column chromatography and a preparative RP-HPLC. The structures were determined by various NMR experiments and by LC/MS and GC/MS analyses. The S1P(1) antagonist activities were measured by a cyclic AMP assay using S1P(1)-expressing cells and the IC(50) values were 8.2 and 1.8 microM, respectively. In a [(33)P]sphingosine-1-phosphate/S1P(1)-binding assay, those values were 120 and 39 microM, and in a migration assay using human umbilical vein endothelial cells (HUVECs), they were 94 and 28 microM, respectively. Thus, ascotricins A and B are novel S1P(1) antagonists showing an inhibition activity toward HUVEC migration.

Colletoic acid, a novel 11beta-hydroxysteroid dehydrogenase type 1 inhibitor from Colletotrichum gloeosporioides SANK 21404.

Colletoic acid, a novel 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) inhibitor, was found and isolated from the cultured broth of the producing fungus Colletotrichum gloeosporioides SANK 21404. Its structure was determined to be a novel acorene-type sesquiterpene by several spectroscopic methods. The absolute structure of colletoic acid was established using a modified Mosher's method and single-crystal X-ray diffraction analysis.