Enzymatic hydrolysis of wood with alkaline treatment     

Dai Oka  Kayoko Kobayashi  Noriyuki Isobe  Yu Ogawa  Tomoya Yokoyama  Satoshi Kimura  Ung-Jin Kim  Ken Tokuyasu  Masahisa Wada 《Journal of Wood Science》2013,59(6):484-488

Pulverized samples of wood, cedar and eucalyptus were treated with 5 N NaOH solutions at 25–150 °C. Hemicellulose and lignin content in the samples decreased with increasing treatment temperatures, while the recovery of glucose was maintained at nearly 90 %. X-ray diffraction analysis showed that the content of the original cellulose I structure in the samples decreased with increasing temperature, and most of the cellulose in the sample treated at 150 °C was converted to cellulose II by mercerization. Enzymatic hydrolysis of the alkaline-treated samples was carried out at 37 °C using solutions comprising a mixture of cellulase and β-glucosidase. The samples treated at higher temperatures showed better enzymatic degradability. Treatment with an alkaline solution of lower concentration (1 N NaOH) at 150 °C was also used. Despite significant quantities of hemicellulose and lignin being removed, mercerization was not induced. The enzymatic degradability was much lower than that of the sample treated with a 5 N NaOH solution at 150 °C. Thus, treatment with concentrated alkaline solution at high temperature led to not only the removal of hemicellulose and lignin, but also to modification of the cellulose structure, which resulted in high efficiency of enzymatic saccharification of the wood samples.  相似文献   

Structural basis of biological N2O generation by bacterial nitric oxide reductase     

Hino T  Matsumoto Y  Nagano S  Sugimoto H  Fukumori Y  Murata T  Iwata S  Shiro Y 《Science (New York, N.Y.)》2010,330(6011):1666-1670

Nitric oxide reductase (NOR) is an iron-containing enzyme that catalyzes the reduction of nitric oxide (NO) to generate a major greenhouse gas, nitrous oxide (N(2)O). Here, we report the crystal structure of NOR from Pseudomonas aeruginosa at 2.7 angstrom resolution. The structure reveals details of the catalytic binuclear center. The non-heme iron (Fe(B)) is coordinated by three His and one Glu ligands, but a His-Tyr covalent linkage common in cytochrome oxidases (COX) is absent. This structural characteristic is crucial for NOR reaction. Although the overall structure of NOR is closely related to COX, neither the D- nor K-proton pathway, which connect the COX active center to the intracellular space, was observed. Protons required for the NOR reaction are probably provided from the extracellular side.  相似文献   

Progress of oxidation of non-phenolic lignin moiety in an oxygen bleaching process via the conversion of non-phenolic into phenolic lignin moiety   总被引：1，自引：1，他引：0  

Satoshi Ohmura  Tomoya Yokoyama  Yuji Matsumoto 《Journal of Wood Science》2012,58(3):243-250

To examine whether non-phenolic lignin moiety is converted into the new phenolic counterpart by the participation of active oxygen species (AOS) under oxygen bleaching conditions, a β-O-4 type dimeric lignin model compound, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)propane-1,3-diol (I), 2-(3,5-difluorophenoxy)-1-(4-hydroxy-3-methoxyphenyl)propane-1,3-diol (III), or 2-(3,5-difluorophenoxy)-1-(3,4-dimethoxyphenyl)propane-1,3-diol (IV), was treated under conditions similar to those for oxygen bleaching. A phenolic compound, 4-hydroxy-3-methoxybenzyl alcohol, was added together to generate AOS in the reaction of compound I or IV. The results obtained suggested that AOS attack the side chains of compounds I, III, and IV accompanied by the β-O-4 bond cleavages and the liberations of the corresponding phenolic compounds, 2-methoxyphenol (II), 3,5-difluorophenol (V), and compound V, respectively. However, the rapid liberation of compound V in the oxygen-alkali treatment of compound III may mainly be caused by alkaline-induced reactions and/or some oxidation reactions of the primary degradation product of compound III, a muconic acid derivative.  相似文献   

Predominant formation of aromatic aldehyde and acid from a dimeric <Emphasis Type="Italic">β</Emphasis>-<Emphasis Type="Italic">O</Emphasis>-4-type lignin model compound under hydrogen peroxide bleaching conditions with high pH levels     

Pattaraporn Posoknistakul  Takuya Akiyama  Tomoya Yokoyama  Yuji Matsumoto 《Journal of Wood Science》2017,63(2):173-182

When a dimeric non-phenolic β-O-4-type lignin model compound, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)propane-1,3-diol (veratrylglycerol-β-guaiacyl ether (VG)), was treated under alkaline oxygen or hydrogen peroxide bleaching conditions (O₂ or H₂O₂ system, respectively), 3,4-dimethoxybenzaldehyde (veratraldehyde) and 3,4-dimethoxybenzoic acid (veratric acid) formed with yields dependent on the system. The yield of veratraldehyde based on the mole amount of disappearing VG (VG disappearance) was about 30% in the O₂ system at a high pH level. However, the total yield of veratraldehyde and veratric acid was 70–80% based on VG disappearance in the H₂O₂ system at high pH levels, where H₂O₂ was added stepwise. A prolonged reaction with the further stepwise addition of H₂O₂ at the high pHs would further increase the formations of veratraldehyde and veratric acid with maintaining the yields based on VG disappearance. The yields (70–80%) are higher than those reported in the previous study, which employed VG, oxygen, and 1,10-phenanthroline and copper (II) sulfate as the catalysts. The high yields in the H₂O₂ system with high pH levels can be explained by the reactivity of oxyl anion radical, which is the most responsible active oxygen species at these high pHs and preferably attacks the aliphatic side-chain of VG rather than the aromatic nucleus.  相似文献   

Natural durability of the culturally and historically important timber: <Emphasis Type="Italic">Erythrophleum fordii</Emphasis> wood against white-rot fungi     

Thanh Duc Nguyen  Hiroshi Nishimura  Tomoya Imai  Takashi Watanabe  Yohsei Kohdzuma  Junji Sugiyama 《Journal of Wood Science》2018,64(3):301-310

The natural resistance of Erythrophleum fordii Oliver wood to degradation by Phanerochaete sordida and Phanerochaete chrysosporium white-rot fungi was investigated. In this study, Fagus crenata Blume (Japanese beech) was selected as reference species. The results showed that both fungi caused less than 2% mass loss in E. fordii wood, while the degradation of beech wood produced by P. chrysosporium and P. sordida was approximately 12 and 14%, respectively. Microscopic observations revealed high structural rigidity of E. fordii timber. Hyphae were only observed in the lumen of vessels and parenchymal cells, while the fibers were not affected. The E. fordii wood fiber consisted of highly lignified thick-walled fibers with the fiber lumina almost completely closed. Two-dimensional heteronuclear single-quantum coherence nuclear magnetic resonance evaluation revealed the E. fordii wood to have a highly condensed-lignin structure that reflected by the durability classes. These unique parameters are likely to be critical for the high natural resistance of E. fordii.  相似文献   

Basal levels and responses to glucose infusion of plasma glucose and insulin in beef steer before and after the end of the growing phase on pasture     

Yasuhiro AOKI  Naoto NAKANISHI  Tomoya YAMADA 《Animal Science Journal》2006,77(3):338-346

We examined the effect of grazing during the growing phase on plasma glucose and insulin behavior at the end of the growing phase and at the early stage of the subsequent fattening phase in beef steers. From 13 to 45 weeks of age (growing phase), crossbred beef steers were grazed with minimal supplement (group G: n = 5) or housed while being fed on hay and concentrate (group H: n = 5). Following this phase, both groups were housed for finishing (fattening phase). At the end of the growing phase, group G showed faster plasma glucose disappearance after intravenous glucose infusion, with a smaller plasma insulin response, compared with group H. At the third week of the fattening phase, group G still showed higher glucose tolerance, although they experienced abrupt changes in nutritional and environmental factors. The results suggest that grazing during the growing phase probably improves the glucose tolerance and insulin response to glucose infusion in steers compared with animals that were housed during the corresponding period, and the improved properties may persist at least a few weeks after the commencement of fattening.  相似文献   

Semi-micro chiral HPLC analysis of lignans     

Tomoya Okunishi  Toshiaki Umezawa  Mikio Shimada 《Journal of Wood Science》2004,50(1):93-96

Chiral high-performance liquid chromatography (HPLC) separation of lignans with semi-micro columns of 1.0–2.0mm inner diameter (i.d.) was established for the first time. Practical sensitivity was increased 5 to 20-fold compared with that of conventional chiral HPLC using analytical columns with 4.6mm i.d. The semi-micro chiral HPLC system can be applied to high-sensitivity enantiomeric separation of many chiral organic compounds in addition to lignans.  相似文献   

Double‐stranded RNA‐mediated silencing of the white spot syndrome virus VP28 gene in kuruma shrimp,Marsupenaeus japonicus     

Raja Sudhakaran  Tomoya Kono  Mari Inada  Shogo Okugawa  Maki Yoshimine  Terutoyo Yoshida  Masahiro Sakai  Toshiaki Itami 《Aquaculture Research》2011,42(8):1153-1162

  相似文献   

Seasonal variations in and effect of incubation water temperature on vertebral number in naturally spawning chum salmon <Emphasis Type="Italic">Oncorhynchus keta</Emphasis>     

Daisei Ando  Yoshihito Shinriki  Yasuyuki Miyakoshi  Hirokazu Urabe  Ryohei Yasutomi  Tomoya Aoyama  Yoshitaka Sasaki  Masamichi Nakajima 《Fisheries Science》2011,77(5):799-807

Seasonal variations and reaction norms for vertebral number (V _N) in response to incubation water temperature were estimated in adult and juvenile naturally spawning chum salmon Oncorhynchus keta. The mean V _N of adults varied according to spawning time; the early-spawning population had higher V _N values than the late-spawning population. Moreover, the mean V _N values in the early-spawning population decreased with seasonal changes, whereas V _N values in the late-spawning population remained stable. Chum salmon embryos in three full-sib families were incubated at five different temperatures until hatching, and the V _N values of the resulting juveniles were analyzed. The V _N reaction norm to incubation water temperature showed a V-shaped curve that was lowest at an intermediate temperature. The mean V _N at the same incubation temperature varied among the three families. These results suggest that V _N values in chum salmon are influenced by genetic components and incubation water temperatures. V _N may be a useful parameter for estimating the environmental conditions during ontogenesis and the genetic background by detecting population changes.  相似文献   

氧漂过程中脱木质素与木质素氧化之间定量关系的研究     

童国林  横山朝哉  松本雄二  飯塚堯介  李忠正 《林产化学与工业》2005,25(4):51-55

对氧碱漂白过程中木质素氧化进行定量分析,分析方法是基于氧化前后高锰酸钾消耗量的变化。该方法对溶出残余木质素的氧化结果分析发现其呈明显3个阶段：第一段木质素氧化的当量电荷数约4～5／木质素单元;木质素总氧化电荷数大约为9／木质素单元。这些数据以及甲氧基的脱除（75％）均表明：木质素的氧化不仅发生在酚型木质素单元,同时也发生在非酚型结构单元上。只有第一阶段氧化反应是木质素与氧气直接反应,而在第二、三阶段主要是协同氧化作用,氧化反应过程中产生的活性氧基团扮演了一定角色。通过对低浓度针叶材硫酸盐浆的氧漂研究发现：当卡伯值下降一半（25．4至13．4）时平均每个木质素单元氧化3当量电子,氧漂后的纸浆中仍然有大量未被氧化的残余木质素。定量地证明了在氧漂过程中木质素氧化是脱木质素反应的实质。  相似文献