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Osamu Hirayama

Bio: Osamu Hirayama is an academic researcher from Kyoto University. The author has contributed to research in topics: Paper chromatography & Polyunsaturated fatty acid. The author has an hindex of 7, co-authored 9 publications receiving 128 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a method is described by which unsaturated fatty acid esters can be separated and identified by reversed-phase paper chromatography, based upon the formation of the mercuric acetate addition compounds of the esters and the detection of the compounds on the chromatograms, using the sensitive color reaction with diphenyl carbazone.
Abstract: A method is described by which unsaturated fatty acid esters can be separated and identified by reversed-phase paper chromatography. The procedure is based upon the formation of the mercuric acetate addition compounds of the esters and the detection of the compounds on the chromatograms, using the sensitive color reaction with diphenylcarbazone. The application of this technique to the analysis of the component unsaturated acids of natural fats has been examined, and tetradecenoic acid in olive oil and hexadecenoic acid in linseed oil both formerly unidentified have been detected as the minor component acids by means of the method. The preliminary investigation on the absorption spectra of diphenylcarbazone complexes derived from the addition compounds has been made to bring the method into quantitative use.

59 citations

Journal ArticleDOI
TL;DR: 玄米「こしひかり」の各複合脂質成分を同定定量し,その約80%を含有していた.
Abstract: 玄米「こしひかり」の各複合脂質成分を同定定量し,その成分組成を明らかにした.糖脂質はステロール系糖脂質およびグリセロ糖脂質からなり,リン脂質はホスファチジル・エタノールアミン,レシチンなどを主成分としていた,全脂質の80%はヌカ層に存在し,残りの20%は胚乳部に分布していた.前者の複合脂質は糖脂質量に富むのに対し,後者のそれはリン脂質と糖脂質の等量からなっていた. 次に,米胚乳部を機械的酵素的に破壊し,水溶性画分,プロテインボディ画分およびデンプン粒画分に分別して,胚乳脂質の分布を調べた.プロテインボディ画分は0.5~4μのタンパク顆粒からなり,胚乳タンパク質の約76%,および胚乳脂質の約80%を含有していた.他方,米胚乳部を溶剤抽出によって水溶性画分,酢酸可溶性画分,スラッジ分およびデンプン粒画分に分画すると,スラッジおよびデンプン粒画分にも,かなりの量の脂質が分布し,上記分画法と異なる結果を示した.これは,細胞内器官の破壊によって成分が遊離し,再配列したためと推測された.また,デンプン粒を破壊して独出した内部脂質は,遊離脂肪酸以外にリゾ型脂質を含む特異な組成を示した.

20 citations

Journal ArticleDOI
TL;DR: In this paper, the simultaneous separations of all saturated and unsaturated fatty acids were successfully carried out on the same paper with the aid of p-bromophenacyl ester 2, 4-dinitrophenylhydrazones and their mercuric acetate addition compounds.
Abstract: By reversed-phase paper chromatography, the simultaneous separations of all saturated and unsaturated fatty acids were successfully carried out on the same paper with the aid of p-bromophenacyl ester 2, 4-dinitrophenylhydrazones and their mercuric acetate addition compounds. When petroleum hydrocarbon (b. p. 140-170°) was used as the stationary solvent and methanol-acetic acid-petroleum hydrocarbon as the moving solvent, even saturated acids from C4 to C22, even monoethenoid acids from C10 to C22, and C18 series from stearic to linolenic were well separated, respectively. Similar separations were also attained on paper impregnated with decalin and olive oil. From the results of several applications, this method has been found to be effective for the analysis of the component acids in natural fats.

10 citations

Journal ArticleDOI
Abstract: 米ヌカ層に存在する脂質分解酵素,リパーゼ,ガラクトリパーゼおよびボスホリパーゼを抽出精製し,その特性を調べた.また,これらの酵素の米貯蔵時における作用を考察した. (1) ゲルろ過, DEAE-セファデックスA-50カラムにより,米ヌカリパーゼ,ガラクトリパーゼ,ホスホリパーゼをそれぞれ100~300倍に純化した.ただし,各酵素を完全に相互分離することはできなかったので,酵素混合物として性質を調べた. (2) 各酵素の分子量はゲルろ過によって,いずれも約4万と推定された. (3) DEAE-セファデックスカラムによって,リパーゼは3成分,ガラクトリパーゼは4成分,そしてホスホリパーゼは2成分に分離された. (4) 蛋白質修飾試薬その他から,リパーゼ活性部位にはセリン残基,ガラクトリパーゼにはセリンおよびシスチン残基,そしてホスホリパーゼにはセリンおよびシステイン(多分)残基が関与していることが示唆された. (5) ヌカGLase, PLaseの活性は光酸化で促進され、ヒスチジン添加で阻害された.しかし,リパーゼ活性はこれらの処理で影響されなかった. (6) 本酵素標品はガラクト脂質,リン脂質のジアシル型およびモノアシル型脂質を脱アシル化した.この場合,ガラクト脂質の1位,トリグリセリドの1, 3位が比較的速く分解され,リン脂質では位置選択性はほとんどみられなかった. (7) 低温貯蔵における玄米の品質低下には,ガラクトリパーゼ,ホスホリパーゼが大きく関与することが推測された.

8 citations


Cited by
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Journal ArticleDOI
TL;DR: The data show that seed ageing slows down significantly, even before seed tissue enters into the glassy state, and this high critical temperature corresponds to the cross-over temperature of glass transition where molecular dynamics changes from a solid-like system to a normal liquid system.
Abstract: Two primary biochemical reactions in seed ageing (lipid peroxidation and non-enzymatic protein glycosylation with reducing sugars) have been studied under different seed water contents and storage temperatures, and the role of the glassy state in retarding biochemical deterioration examined. The viability loss of Vigna radiata seeds during storage is associated with Maillard reactions; however, the contribution of primary biochemical reactions varies under different storage conditions. Biochemical deterioration and viability loss are greatly retarded in seeds stored below a high critical temperature (approximately 40 ∞C above glass transition temperature). This high critical temperature corresponds to the cross-over temperature (Tc) of glass transition where molecular dynamics changes from a solid-like system to a normal liquid system. The data show that seed ageing slows down significantly, even before seed tissue enters into the glassy state.

219 citations

Journal ArticleDOI
TL;DR: In this article, a new method was described for the isolation of nearly pure total cerebrosides from fresh brain, where Florisil columns were used to separate cerebroside hydroxy and normal acids, in the form of their esters, and to separate the saturated and unsaturated esters of each group.

152 citations

Journal ArticleDOI
TL;DR: Three Arabidopsis mutants, acx1acx2, lacs6lacs7, and kat2, are examined, indicating that several mutations in β-oxidation that cause reduced breakdown of reserve oil in seeds do not substantially reduce the degradation of fatty acids during leaf senescence.
Abstract: During leaf senescence, macromolecule breakdown occurs and nutrients are translocated to support growth of new vegetative tissues, seeds, or other storage organs. In this study, we determined the fatty acid levels and profiles in Arabidopsis (Arabidopsis thaliana), Brachypodium distachyon, and switchgrass (Panicum virgatum) leaves during natural senescence. In young leaves, fatty acids represent 4% to 5% of dry weight and approximately 10% of the chemical energy content of the leaf tissues. In all three species, fatty acid levels in leaves began to decline at the onset of leaf senescence and progressively decreased as senescence advanced, resulting in a greater than 80% decline in fatty acids on a dry weight basis. During senescence, Arabidopsis leaves lost 1.6% of fatty acids per day at a rate of 2.1 mug per leaf (0.6 mug mg(-1) dry weight). Triacylglycerol levels remained less than 1% of total lipids at all stages. In contrast to glycerolipids, aliphatic surface waxes of Arabidopsis leaves were much more stable, showing only minor reduction during senescence. We also examined three Arabidopsis mutants, acx1acx2, lacs6lacs7, and kat2, which are blocked in enzyme activities of beta-oxidation and are defective in lipid mobilization during seed germination. In each case, no major differences in the fatty acid contents of leaves were observed between these mutants and the wild type, indicating that several mutations in beta-oxidation that cause reduced breakdown of reserve oil in seeds do not substantially reduce the degradation of fatty acids during leaf senescence.

150 citations

Journal ArticleDOI
TL;DR: Among the bacterial strains known to contain ubiquinone-10, three strains, Agrobacterium tumefaciens KY-3085, Paracoccus denitrificans KY-3940 and Rhodobacter sphaeroides KY-4113, were selected as excellent producers of this ubiquin one.
Abstract: Among the bacterial strains known to contain ubiquinone-10, three strains, Agrobacterium tumefaciens KY-3085 (ATCC4452), Paracoccus denitrificans KY-3940 (ATCC19367) and Rhodobacter sphaeroides KY-4113 (FERM-P4675), were selected as excellent producers of this ubiquinone. The ubiquinone-10 production by the Agrobacterium and Rhodobacter strains was affected by aeration. An ethionine-resistant mutant (M-37) derived from A. tumefaciens KY-3085 promoted increased production of ubiquinone-10 (20% higher than the parent). Another Agrobacterium mutant (AU-55), which was induced by the successive addition of four genetic markers, showed a tolerance to the suppression of ubiquinone-10 production caused by aeration, and the fermentation time for production was remarkably shortened. The amount of ubiquinone-10 produced by this Agrobacterium mutant reached 180 mg/l in a 58 h culture. A green mutant (carotenoid-deficient mutant, Co-22-11) derived from R. sphaeroides KY-4113 produced 350 mg/l of ubiquinone-10 under culturing conditions with a limited supply of air, the ubiquinone-10 content being 8.7 mg/g-dry cell. In this case, the amount and content corresponded to 2.8 and 3.6 times larger than those given by the wild-type strain, respectively. A multiple-layer structure of cell membrane was observed in the highly ubiquinone-10 accumulating cell of the green mutant by electron microscopy. The amount of ubiquinone-10 produced by P. denitrificans was much lower than those of the other two strains.

117 citations