Sachio Yamamoto

Bio: Sachio Yamamoto is an academic researcher. The author has contributed to research in topics: Solubility & Monosaccharide. The author has an hindex of 3, co-authored 3 publications receiving 757 citations.

Solubility of methane in distilled water and seawater

Abstract: Bunsen solubility coefficients for methane in distilled water and in seawater at three salinities were determined with an estimated accuracy of 0.5 YO. The experimental data were fit by the least-squares method to an equation established by Weiss. A table of Bunsen solubility coefficients covering the temperature range -2' to 3OoC and the salinity range 0-40 parts per thousand was calculated from the fitted equation. For seawater of salinity 34%0, the Bunsen coefficients ranged from 0.04489 at O°C to 0.02368 at 3OoC. Solubility values for distilled water were in agreement with those reported by Bunsen and Claussen and Polglase but were 34% higher than those of Winkler and Morrison and Billet.

光重合性Phos-tag含有アクリルアミドゲルを用いるリン酸化化合物の高感度検出システムの開発

Abstract: タンパク質におけるリン酸化・脱リン酸化は，シグナル伝達，転写および翻訳調節，代謝などの調節に重要な役割を果たす。このタンパク質のリン酸化を網羅的に解明するリン酸化プロテオミクスにおいては質量分析装置 (MS)あるいはLC-MSなどを用いた網羅的な解析が実施されている。しかしながら試料溶液中に存在する非リン酸化ペプチドによりリン酸化ペプチドのイオン化が抑制され，MSによるリン酸化ペプチドの感度低下が問題となることが多い。この問題を解決するために，リン酸化化合物を特異的に濃縮するための様々な方法が開発されている。この中で1,3-bis[bis(pyridin-2-ylmethyl)amino]propan-2-ol (Phos-tag)は，このリン酸基を特異的に認識する化合物であり，SDS-PAGEなどでリン酸化タンパク質の特異的検出に利用されている。我々はこのPhos-tagを含有したアクリルアミドゲルをマイクロチップの流路の一部にピンポイントで作製する技術を開発し，リン酸化ペプチドのマイクロチップ流路中での特異的濃縮法とリン酸化化合物のオンライン濃縮・蛍光標識化法を開発した。

A rapid and convenient enzyme digestion method for the analysis of N-glycans using exoglycosidase-impregnated polyacrylamide gels fabricated in an automatic pipette tip

Abstract: Efficient enzymatic digestion methods are critical for the characterization and identification of glycans. Glycan hydrolysis enzymes are widely utilized for the identification of glycoprotein or glycolipid glycans. The commonly utilized in solution glycan hydrolysis methods require several hours of incubation with enzymes for complete removal of their target monosaccharides. To develop an efficient and simple method for the rapid release of monosaccharides from glycoprotein glycans, we fabricated exoglycosidase-impregnated acrylamide gels in an automatic pipette tip. Our automated enzymatic reactors are based on the simple photochemical copolymerization of monomers comprising acrylamide and methylene-bis-acrylamide-containing enzymes with an azobis compound functioning as the photocatalytic initiator. After filling the tip of the automatic pipette with these acrylamide solutions, polymerization of the acrylamide gel solution was performed by irradiation with a LED. The immobilized enzymes maintained their activities in the pipette tips and their action was completed by fully automatic pipetting for 10 to 30 min. We utilized 8-aminopyrene-1, 3, 6-trisulfonic acid (APTS)-labeled glycans as a substrate and measured by capillary electrophoresis (CE) before and after enzymatic digestion. We demonstrated that this method exhibited quantitative enzymatic and specific cleavage of monosaccharides from glycoprotein glycans.

Gas hydrates—geological perspective and global change

Abstract: Gas hydrates are naturally ocurring solids consisting of water molecules forming a lattice of cages, most of which contain a molecule of natural gas, usually methane. The present article discusses three important aspects of gas hydrates: their potential as a fossil fuel resource, their role as a submarine geohazard, and their effects on global climate change. 70 refs., 16 figs., 1 tab.

Oceanic methane biogeochemistry.

Abstract: This review shows that thermodynamic and kinetic constraints largely prevent large-scale methanogenesis in the open ocean water column. One example of open-ocean methanogenesis involves anoxic digestive tracts and fecal pellet microenvironments; methane released during fecal pellet disaggregation results in the mixed-layer methane maximum. However, the bulk of the methane in the ocean is added by coastal runoff, seeps, hydrothermal vents, decomposing hydrates, and mud volcanoes. Since methane is present in the open ocean at nanomolar concentrations, and since the flux to the atmosphere is small, the ultimate fate of ocean methane additions must be oxidation within the ocean. As indicated in the Introduction and highlighted in Table 3, sources of methane to the ocean water column are poorly quantified. There are only a small number of direct water column methane oxidation rates, so sinks are also poorly quantified. We know that methane oxidation rates are sensitive to ambient methane concentrations, but we have no information on reaction kinetics and only one report of the effect of pressure on methane oxidation. Our perspective on methane sources and the extent of methane oxidation has been changed dramatically by new techniques involving gene probes, determination of isotopically depleted biomarkers, and recent 14C-CH4 measurements showing that methane geochemistry in anoxic basins is dominated by seeps providing fossil methane. The role of anaerobic oxidation of methane has changed from a controversial curiosity to a major sink in anoxic basins and sediments. © 2007 American Chemical Society.

Field and laboratory studies of methane oxidation in an anoxic marine sediment: Evidence for a methanogen-sulfate reducer consortium

Abstract: Field and laboratory studies of anoxic sediments from Cape Lookout Bight, North Carolina, suggest that anaerobic methane oxidation is mediated by a consortium of methanogenic and sulfate-reducing bacteria. A seasonal survey of methane oxidation and CO2 reduction rates indicates that methane production was confined to sulfate-depleted sediments at all times of year, while methane oxidation occurred in two modes. In the summer, methane oxidation was confined to sulfate-depleted sediments and occurred at rates lower than those of CO2 reduction. In the winter, net methane oxidation occurred in an interval at the base of the sulfate-containing zone. Sediment incubation experiments suggest both methanogens and sulfate reducers were responsible for the observed methane oxidation. In one incubation experiment both modes of oxidation were partially inhibited by 2-bromoethanesulfonic acid (a specific inhibitor of methanogens). This evidence, along with the apparent confinement of methane oxidation to sulfate-depleted sediments in the summer, indicates that methanogenic bacteria are involved in methane oxidation. In a second incubation experiment, net methane oxidation was induced by adding sulfate to homogenized methanogenic sediments, suggesting that sulfate reducers also play a role in the process. We hypothesize that methanogens oxidize methane and produce hydrogen via a reversal of CO2 reduction. The hydrogen is efficiently removed and maintained at low concentrations by sulfate reducers. Pore water H2 concentrations in the sediment incubation experiments (while net methane oxidation was occurring) were low enough that methanogenic bacteria could derive sufficient energy for growth from the oxidation of methane. The methanogen-sulfate reducer consortium is consistent not only with the results of this study, but may also be a feasible mechanism for previously documented anaerobic methane oxidation in both freshwater and marine environments.