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Biodegradable polymer-photosensitizer composites were developed, which is suppressed biodegradation due to bactericidal activity under light irradiation but proceeds under dark conditions. The composites exhibited antibacterial activity under light irradiation, which was attributed to the generation of singlet oxygen (1O2). Biodegradation was evaluated in seawater using the biochemical oxygen demand (BOD) method. In the dark, the composite and base polymer biodegraded to a similar degree. However, under light irradiation, the biodegradation of the composite was suppressed. In field tests, the rate of volume reduction of the composites decreased under illumination. The main cause of the suppression of biodegradation is suggested to be due to the decrease in the number of bacteria on the surface of the material and the inactivation of exoenzymes. The findings are expected to contribute to the development of biodegradable polymers that do not biodegrade during use but only when disposed of in the environment, thereby achieving on-demand degradation.

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We have previously reported that sequence-controlled copolyesters such as poly((ethylene diglycolate) terephthalate) (poly(GEGT)) showed higher melting temperatures than those of the corresponding random copolymers and high biodegradability in seawater. In this study, to elucidate the effect of the diol component on their properties, a series of new sequence-controlled copolyesters composed of glycolic acid, 1,4-butanediol or 1,3-propanediol, and dicarboxylic acid units was studied. 1,4-Butylene diglycolate (GBG) and 1,3-trimethylene diglycolate (GPG) were prepared by the reactions of 1,4-dibromobutane or 1,3-dibromopropane with potassium glycolate, respectively. Polycondensation of GBG or GPG with various dicarboxylic acid chlorides produced a series of copolyesters. Terephthalic acid, 2,5-furandicarboxylic acid, and adipic acid were used as the dicarboxylic acid units. Among the copolyesters bearing terephthalate or 2,5-furandicarboxylate units, the melting temperatures (Tm) of the copolyesters containing 1,4-butanediol or 1,2-ethanediol units were substantially higher than those of the copolyester containing the 1,3-propanediol unit. Poly((1,4-butylene diglycolate) 2,5-furandicarboxylate) (poly(GBGF)) showed a Tm at 90 °C, while the corresponding random copolymer was reported to be amorphous. The glass-transition temperatures of the copolyesters decreased as the carbon number of the diol component increased. Poly(GBGF) was found to show higher biodegradability in seawater than that of poly(butylene 2,5-furandicarboxylate) (PBF). On the other hand, the hydrolysis of poly(GBGF) was suppressed in comparison with that of poly(glycolic acid). Thus, these sequence-controlled copolyesters have both improved biodegradability compared to PBF and lower hydrolyzability than PGA.

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An innovative type of biodegradable thermoplastic elastomers with improved mechanical properties from very common and potentially renewable sources, poly(L-lactide)-b-poly(2-methyl-1,3-propylene glutarate)-b-poly(L-lactide) (PLA-b-PMPG-b-PLA)s, has been developed for the first time. PLA-b-PMPG-b-PLAs were synthesized by polycondensation of 2-methyl-1,3-propanediol and glutaric acid and successive ring-opening polymerization of L-lactide, where PMPG is an amorphous central block with low glass transition temperature and PLA is hard semicrystalline terminal blocks. The copolymers showed glass transition temperature at lower than -40 °C and melting temperature at 130-152 °C. The tensile tests of these copolymers were also performed to evaluate their mechanical properties. The degradation of the copolymers and PMPG by enzymes proteinase K and lipase PS were investigated. Microbial biodegradation in seawater was also performed at 27 °C. The triblock copolymers and PMPG homopolymer were found to show 9-15% biodegradation within 28 days, representing their relatively high biodegradability in seawater. The macromolecular structure of the triblock copolymers of PLA and PMPG can be controlled to tune their mechanical and biodegradation properties, demonstrating their potential use in various applications.

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Poly(ester amide)s are attracting attention because they potentially have excellent thermal and mechanical properties as well as biodegradability. In this study, we synthesized a series of novel poly(ester amide)s by introducing γ-aminobutyric acid (GABA) regularly into polyesters, and investigated their properties and biodegradabilities. GABA is the monomer unit of biodegradable polyamide 4 (PA4). The new poly(ester amide)s were synthesized from the reaction of ammonium tosylate derivatives of alkylene bis(γ-aminobutylate) and p-nitrophenyl esters of dicarboxylic acids. All the obtained polymers showed relatively high melting temperatures (Tm). Their thermal decomposition temperatures were improved in comparison with that of PA4 and higher enough than their Tm. The poly(ester amide)s exhibited higher biodegradability in seawater than the corresponding homopolyesters. Their biodegradabilities in activated sludge were also studied.

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4-Aminobutylic acid (GABA) is a monomer of plastic polyamide 4. Bio-based polyamide 4 can be produced by using GABA obtained from biomass. The production of L-glutamic acid (Glu) from biomass has been established. GABA is produced by decarboxylation of Glu in biological process. High-performance liquid chromatography (HPLC) with derivatization is generally used to determine the concentration of GABA and Glu in reacted solution samples for the efficient production of GABA. In this study, we have investigated the rapid determination of GABA and Glu by capillary electrophoresis-mass spectrometry (CE-MS) without derivatization. The determination was achieved with the use of a shortened capillary, a new internal standard for GABA, and optimization of sheath liquid composition. Determined concentrations of GABA and Glu by CE-MS were compared with those by pre-column derivatization HPLC with phenylisothiocyanate. The determined values by CE-MS were close to those by HPLC with pre-column derivatization. These results suggest that the determination of GABA and Glu in reacted solution is rapid and simplified by the use of CE-MS.

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Glutamate decarboxylase (GAD) from the archaeon Pyrococcus horikoshii was successfully expressed and purified, with the aim of developing a hyperthermostable GAD for industrial applications. Its biochemical properties were different from those reported for other GADs. The enzyme had broad substrate specificity, and its optimum pH and temperature were pH 8.0 and > 97 degrees C.

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OBJECTIVE: Shoseiryuto (TJ-19) contains eight herbal components, including Ephedra sinica, and has been used for treating asthma and allergic rhinitis in Asian countries for several centuries. In this study, we investigated the potential herb-drug interaction of TJ-19 in healthy volunteers and attempted to ascertain whether or not the interaction might be affected by the cytochrome P450 (CYP) 2D6 genotype. METHODS: We assessed the effect of TJ-19 on the activities of CYP1A2, CYP2D6, CYP3A, xanthine oxidase (XO), and N-acetyltransferase 2 (NAT2) in 37 healthy subjects. The subject pool consisted of 19 extensive metabolizers (EMs) with CYP2D6*Wild/*Wild, and 18 intermediate metabolizers (IMs) with CYP2D6*10/*10. The baseline activities of five enzymes were ascertained by their respective urinary metabolic ratios from an 8-h urine sample, after an oral 150-mg and 30-mg dose of caffeine and dextromethorphan were administrated, respectively. Thereafter, the subjects received 4.5 g of TJ-19 twice daily for 7 days, and underwent the same phenotyping test on postdose day 7. RESULTS: The activities of all enzymes examined did not differ before or after the 7-day administration of TJ-19. Consequently, the influence of the CYP2D6 genotype on the herb-drug interaction remained unsolved. CONCLUSION: Our results indicate that TJ-19 at the generally recommended dosage is unlikely to cause pharmacokinetic interaction with co-administered medications primarily dependent on the CYP1A2, CYP2D6, CYP3A, XO, and NAT2 pathways for elimination.

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The selective and efficient production of N-acetyl-D-glucosamine (GlcNAc) was achieved from flake type of alpha-chitin by using crude enzymes derived from Aeromonas hydrophila H-2330.

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