トリアジニルスチルベン系直接染料型蛍光増白染料(置換基:アニリノ基,2-ヒドロキシエチルアミノ基)の水中における溶解性と光退色挙動を調べた。露光によるUVおよび蛍光スペクトルの変化,TLCの結果から,溶解状態の染料は,trans-cis の可逆的光異性化を起こして cis-体の多い定常状態に達し,また染料濃度が高いほど cis-体の割合が多いことがわかった。水中での溶解性は染料濃度,温度,pHに影響され,高濃度,低温度,低pHでは染料が凝集して,可視部に新たな吸収(Λmax:420nm)のが生じ,溶解状態の染料にくらべ退色しにくいことがわかった。

10.1246/nikkashi.1987.101

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Enhanced Production of Rebaudioside D and Rebaudioside M through V155T Substitution in the Glycosyltransferase UGT91D2 from Stevia rebaudiana

Journal of Agricultural and Food Chemistry (2025)

Tsubasa Shoji Yoshikazu Tanaka Yu Nakashima Eiichi Mizohata Motoko Komaki

Steviol glycosides (SGs) are noncaloric natural sweeteners found in the leaves of stevia (Stevia rebaudiana). These diterpene glycosides are biosynthesized by attaching varying numbers of monosaccharides, primarily glucose, to steviol aglycone. Rebaudioside (Reb) D and Reb M are highly glucosylated SGs that are valued for their superior sweetness and organoleptic properties, yet they are present in limited quantities in stevia leaves. This study aims to improve the substrate preference and catalytic efficiency of UDP-sugar-dependent glycosyltransferase UGT91D2 from stevia, which acts as a bottleneck in the biosynthesis of Reb D and Reb M. We modeled the structure of UGT91D2 and substituted two amino acid residues, Y134 and V155, which are located near the glycosyl acceptor and donor, respectively. Expression of the UGT91D2V155T in budding yeast significantly enhanced the production of Reb D and Reb M. Furthermore, transient expression in Nicotiana benthamiana revealed that the V155T substitution improved the glucosylation activity of UGT91D2, suggesting that this substitution enhances UDP-glucose binding and reduces side reactions involving nonglucose donors. By coexpressing multiple stevia UGT genes in N. benthamiana, we successfully produced highly glucosylated SGs from steviol. Our results provide insights into the substrate specificity of UGT91D2 and contribute to the engineering of SG biosynthesis.

Steviol

Stevia rebaudiana

Rebaudioside A

Aglycone

Sweetness

Stevia

10.1021/acs.jafc.4c09392

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The Lowering of Strength of the Drawn Tape of Ultra-high-molecular-weight Polypropylene by the Irradiation with Xenon Arc Lamp

Sen i Gakkaishi (2010)

Yukiko Ikeda Motoko Komaki

It was investigated from a practical point of view the influence of light irradiation on the strength of drawn tape of ultra-high-molecular-weight polypropylene (UHMW-PP) prepared by the gel-casting (GC) method and the gel-like spherulite press (GSP) method. Consequently, it was found that the irradiated GC sheets prepared from 1, 2, 4 and 6 wt.% solutions had different tendencies on the change of strength by ultra-drawing. The ratio of lowering of strength increased with increase in draw ratio of both GC and GSP sheets, especially GC sheet.

Polypropylene

10.2115/fiber.66.78

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Influence of detergent builders on surface properties of sodium dodecyl sulfate solutions under dynamic and static conditions

Journal of the American Oil Chemists Society (1990)

Michiko Kimura Motoko Komaki Toshinari Nakajima Hiroo Nakahara Kiyoshige Fukuda

The effects of various detergent builders on surface properties of sodium dodecyl sulfate (SDS) solutions have been investigated by measuring the equilibrium surface tension and hysteresis curves of surface pressure vs surface area under dynamic conditions. While the adsorbed layer of SDS under static conditions is in the liquid‐expanded state, a two‐dimensional phase transition of the adsorbed layer from liquid‐expanded to condensed‐film can be observed on compression at higher rates beyond the saturated adsorption. For the SDS solution containing excess NaCl (1×10 −1 M), the adsorbed layer of SDS is already in the condensed state under static condition due to a depression in the dissociation of SDS. It has been found that some polyelectrolytes, as well as conventional ionic builders, contribute to increasing the surface excess concentration of SDS together with promoting micelle formation and also to stabilizing the adsorbed layer of SDS. On the other hand, poly(vinyl alcohol) (PVA) as a nonionic polymer is adsorbed at the air‐water interface in preference to SDS. In this case, the hysteresis of the dynamic surface behavior of the mixed solution can be attributed to the structural change of the adsorbed layer of PVA rather than SDS, which is different from the other ionic builders.

Sodium dodecyl sulfate

Surface pressure

10.1007/bf02540425

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Washing Method by Introducing Air into an Alternating Flow System

Journal of Oleo Science (2006)

Masahiro Karasawa Tomiichi HASEGAWA Motoko Komaki Takatsune NARUMI

To establish an effective washing method, experiments were conducted on an alternating flow system to bring about the flow through fabric material and the deformation of fabric. Air was introduced into an alternating flow so that less detergent would be required for washing. Examination was made of, concentration of detergent, washing time, and the effect of the amount of air on detergency. By applying the present method to the washing solutions of concentration over c.m.c, it was clearly shown the possibility of decreasing the amount of detergent as much as 50 % with no reduction in detersive efficiency. It was also shown that the detersive efficiency is related to the dynamic surface tension.

Alternating current

10.5650/jos.55.521

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Effect of Zeolite on the Dispersion Stability of Iron Oxide Particles

Textile Research Journal (1986)

Michiko Kimura Motoko Komaki Akihiko Yabe

The mechanisms of zeolite that contribute to the dispersion stability of iron oxide were investigated. It was evident that an interaction exists between iron oxide and zeolite by the sedimentation method and absorbance measurements. Moreover, zeolite enhances the dispersion stability of iron oxide particles. This study proves that zeolite exerts an effect of increasing pH, which is one of the mechanisms that contributes to the dispersion stability of iron oxide particles.

Dispersion stability

Sedimentation

Absorbance

10.1177/004051758605600504

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KINETICS AND MECHANISM OF HYDROLYSIS OF REACTIVE DYES IN SOLUTION

Sen i Gakkaishi (1973)

Motoko Komaki Tomoko Kaneda Masako Hayashi Akihiko Yabe Mitsuhiko Hida

The kinetics and mechanism of alkaline hydrolysis of chlorotriazinyl reactive dyes containing imino groups have been studied at constant temperature over a range of pH values and dye concentrations by a paper chromatography.The results obtained were explained in terms of the apparent second-order rate constant, and the hydrolysis was independent of dye concentration, but was dependent on pH of the dye liquor.This could be explained by assuming that an acid-base equilibrium exists at imino bridged group of the dye. As is generally accepted, both values of dissociation constant (K) of imino bridged groups and the true rate constant (k) were expected to be increased by the substituent, having electron donating character. And this substitution effect was found to be larger at meta position than at para position.

Dissociation constant

Hydrolysis constant

Hammett equation

Acid dissociation constant

Reactive dye

10.2115/fiber.29.12_t546

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