Faculty Profiles - IMAMURA Koreyoshi

MISC - IMAMURA Koreyoshi

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Kinetics and equilibrium for thermolysin-catalyzed syntheses of dipeptide precursors in aqueous/organic biphasic systems

M Miyanaga, M Ohmori, K Imamura, T Sakiyama, K Nakanishi

JOURNAL OF BIOSCIENCE AND BIOENGINEERING 90 ( 1 ) 43 - 51 2000.7

Language：English Publisher：SOC BIOSCIENCE BIOENGINEERING JAPAN

The initial kinetics for the syntheses of N-(benzyloxycarbonyl)-L-alanyl-L-phenylanine methyl ester (ZAPM) and N-(benzyloxycarbonyl)-L-aspartyl-L-phenylalanine methyl ester (ZDPM) in an aqueous/organic biphasic system, using free thermolysin were elucidated, both experimentally and theoretically. As model organic solvents, ethyl acetate and tert-amyl alcohol were used. The substrate concentration dependencies of the initial rate of syntheses for ZAPM and ZI)PM observed in the biphasic system were well simulated using the overall partition coefficients of the substrates and product taking into consideration the effect of the formation of ion-pair complexes between the acid and amine components of the substrate, the initial rate equations determined in an aqueous buffer saturated with the organic solvent, and the pH dependence of the rate constant. The equilibrium yield for the synthesis of ZDPM was also in good agreement with the calculated result using the overall partition coefficients and equilibrium constant measured in the aqueous buffer.

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Kinetic analysis for synthesis of a dipeptide precursor using an immobilized enzyme in water-immiscible organic solvents

M Miyanaga, K Imamura, T Sakiyama, K Nakanishi

JOURNAL OF BIOSCIENCE AND BIOENGINEERING 90 ( 1 ) 112 - 114 2000.7

Language：English Publisher：SOC BIOSCIENCE BIOENGINEERING JAPAN

N-(Benzyloxycarbonyl)-L-aspartyl-L-phenylalanine methyl ester (Z-AspPheOMe), a precursor of the synthetic sweetener aspartame, was synthesized, using thermolysin immobilized onto Amberlite XAD-7, both in ethyl acetate and in tert-amyl alcohol. The initial rates for synthesis of Z-AspPheOMe in the organic solvents were predicted on the basis of a model proposed for an aqueous/organic biphasic reaction and compared with the experimentally observed substrate concentration dependencies. The experimental synthetic rates using the enzyme immobilized at a high enzyme concentration were lower than the calculated ones over a wide range of the substrate concentration. It was suggested as a reason for this discrepancy that the enzyme molecules form compact aggregates and those existing inside the aggregates cannot be utilized for reaction. The experimental results with the enzyme immobilized at a low concentration in ethyl acetate coincided well with the calculated ones. On the other hand, when tert-amyl alcohol was used, the experimental results were different in tendency irrespective of the amount of enzyme loaded, probably due to the fact that a distinct water phase does not exist around the enzyme aggregates inside the support.

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Development of novel advanced oxidation system using combined UV/H2O2 technique and kinetic analysis for decomposition of dye solutions

K Imamura, A Hiramatsu, M Imada, T Sakiyama, A Tanaka, Y Yamada, K Nakanishi

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 33 ( 2 ) 253 - 261 2000.4

Language：English Publisher：SOC CHEMICAL ENG JAPAN

A novel advanced oxidation system using a combined UV/H2O2 technique was constructed for application to wastewater treatment. In this system, wastewater containing H2O2 flows along a channel with a flat surface in a thin film, onto which surface UV rays with a wavelength of 253.7 nm are irradiated. As a model wastewater, we used various dye solutions and investigated decoloration rates under various conditions differing in H2O2 concentration, temperature, UV illuminance, and so on. Based on the model, which takes into consideration the formation as well as the disappearance rate of hydroxyl radical (. OH), distribution of UV illuminance along the depth of the flow, and the rate of reaction between dye and . OH, we could simulate the course of dye decomposition. Furthermore, we showed the existence of an optimum H2O2 concentration for decomposition on the basis of this model.

DOI： 10.1252/jcej.33.253

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膜面液体培養法を用いた海洋植物プランクトンOscillatoria属の培養と特性解明

中西一弘, 崎山高明, 今村維克

財団法人ソルト・サイエンス研究財団助成研究報告集 1998 ( 1 ) 279 - 286 2000.3

BSAを含有した糖アモルファスの水分収着およびガス転移

Journal of Chemical Engineering of Japan 33 ( 4 ) 657 - 660 2000

紫外線/H₂O₂処理を利用した新規促進酸化システムの開発と色素水溶液の分解過程の速度論の解析

33 ( 2 ) 253 - 261 2000

Increase in the stability of serine acetyltransferase from Escherichia coli against cold inactivation and proteolysis by forming a biezyme complex

Mino Koshiki, Imamura Koreyoshi, Sakiyama Takaharu, Eisaki Naoki, Matsuyama Asahi, Nakanishi Kazuhiro, RITE

12 225 - 225 2000

Synthesis of capsaicin analogues by aminoacylase.

Koreishi Mayuko, Kamakura Kaoru, Imamura Koreyoshi, Sakiyama Takaharu, Adachi Syuji, Matsuno Ryuichi, Nakanishi Kazuhiro

12 218 - 218 2000

Enzymatic synthesis of N-acylamino acids in cosolvents.

Wada Eiko, Handa Masato, Imamura Koreyoshi, Sakiyama Takaharu, Adachi Shuji, Matsuno Ryuichi, Nakanishi Kazuhiro

12 219 - 219 2000

Synthesis of nonproteinous amino acid by cysteine synthetase with acetyl-CoA regeneration system.

Ohno Katsuhiro, Mino Koshiki, Imamura Koreyoshi, Sakiyama Takaharu, Eisaki Naoki, Matsuyama Asahi, Nakanishi Kazuhiro

12 218 - 218 2000

Maintenance of protein structure in dry state by amorphous sugar

Imamura Koreyoshi, Ogawa Tomohiro, Sakiyama Takaharu, Nakanishi Kazuhiro

12 280 - 280 2000

Analysis for partition equilibrium of amino acid derivatives in aqueous/organic biphasic systems

M Miyanaga, K Imamura, K Tanaka, T Sakiyama, K Nakanishi

JOURNAL OF BIOSCIENCE AND BIOENGINEERING 88 ( 6 ) 651 - 658 1999.12

Language：English Publisher：SOC BIOSCIENCE BIOENGINEERING JAPAN

The overall partition coefficients of the acid and amine components of amino acid derivatives, the substrates for proteinase-catalyzed synthesis of oligopeptide precursors, in an aqueous/organic biphasic system were studied both experimentally and theoretically. In a single-component system containing either an acid or amine component, the overall partition coefficient was well expressed by a model using the acid dissociation constant and partition coefficients for the non-ionized and ionized forms of the component. The overall partition coefficient in a binary-component system containing both acid and amine components was well simulated by the model when the formation of ion-pair complexes in the organic solvent phase was taken into consideration in addition to the partitioning of the non-ionized and ionized forms of the components. The formation of ion-pair complexes in the organic solvent phase was indicated by an analysis using Fourier transform infrared ray spectroscopy (FT-IR). In addition to the partition equilibrium, the aqueous-phase pH change after partitioning could be predicted by the model.

DOI： 10.1016/S1389-1723(00)87095-4

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Adsorption characteristics of tryptic fragments of bovine beta-lactoglobulin on a stainless steel surface

T Sakiyama, K Tanino, M Urakawa, K Imamura, T Takahashi, T Nagai, K Nakanishi

JOURNAL OF BIOSCIENCE AND BIOENGINEERING 88 ( 5 ) 536 - 541 1999.11

Language：English Publisher：SOC BIOSCIENCE BIOENGINEERING JAPAN

As a strategy for the analysis of the mode of protein adsorption onto stainless steel surfaces, peptides obtained by tryptic digestion of bovine beta-lactoglobulin were subjected to adsorption experiments after identification of their primary structures. In the presence of I mM KOH, the peptides were scarcely adsorbed onto the surfaces of stainless steel particles from the peptide mixture. The adsorption experiments on isolated peptides showed that the affinities of the peptides for stainless steel surfaces in the presence of 1 mM HNO3 were significantly different from each other. Peptides without any acidic amino acid residues were scarcely adsorbed onto the surface, whereas some peptides with acidic amino acid residues were found to be irreversibly adsorbed onto the surfaces in the acidic pH region. As for the latter peptides, the amount adsorbed on the surface increased with increasing ionic strength. These results indicated that the carboxyl groups on the side chains of the peptides play an important role in the adsorption. Furthermore, the adsorption behavior of beta-lactoglobulin itself was found to be very similar to that of one of the latter peptides.

DOI： 10.1016/S1389-1723(00)87672-0

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Stability of immobilized thermolysin in organic solvents

M Miyanaga, M Ohmori, K Imamura, T Sakiyama, K Nakanishi

JOURNAL OF BIOSCIENCE AND BIOENGINEERING 87 ( 4 ) 463 - 472 1999.4

Language：English Publisher：SOC BIOSCIENCE BIOENGINEERING JAPAN

Various factors affecting the stability of thermolysin immobilized by cross-linking with glutaraldehyde were elucidated, particularly in the water-immiscible organic solvents such as ethyl acetate and tert-amyl alcohol. The main reason for enzyme inactivation in water-immiscible organic solvents was found to be autolysis in the water phase, which may surround the enzyme immobilized inside the support. By contrast, in water-miscible organic solvents thermal denaturation was the predominant cause of enzyme inactivation. Courses of inactivation were expressed by second-order kinetics in the initial stage, after which inactivation proceeded at a slower rate. The extent of autolysis was found to strongly depend on the kind of organic solvent, the water content, and type of support and these dependencies were explained by the difference in the amount and state of water inside the support. Thermolysin was immobilized onto Amberlite XAD-7 as a compact aggregate inside the support which may increase the stability of the enzyme. Finally, it was shown that the stability of the immobilized enzyme could be correlated with the logP value for water-miscible organic solvents and with the solubility of water for water- immiscible organic solvents.

DOI： 10.1016/S1389-1723(99)80095-4

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食品製造・バイオプロセスにおける洗浄とタンパク性汚れの付着(<特集>殺菌・洗浄のバイオテクノロジー)

中西一弘, 今村維克, 崎山高明

生物工学会誌 : seibutsu-kogaku kaishi 77 ( 6 ) 241 - 245 1999

Characteristics and kinetics of cysteine synthetase from Escherichia coli.

Mino Koshiki, Imamura Koreyoshi, Sakiyama Takaharu, Eisaki Naoki, Matsuyama Asahi, Nakanishi Kazuhiro, RITE

11 170 - 170 1999

Adsorption behaviors of protein, peptide, and amino acid onto stainless steel surface

Imamura Koreyoshi, Sato Masako, Tomura Junji, Okamoto Makoto, Sakiyama Takaharu, Nakanishi Kazuhiro, Takahashi Tokio, Nagai Tadashi

11 333 - 333 1999

Production of pigment from Monascus pilosus k using membrane surface liquid culture

Tsushima Youko, Mino Akira, Imamura Koreyoshi, Sakiyama Takaharu, Nakanishi Kazuhiro, Suga Sadaharu, Danou Yasuhumi

11 220 - 220 1999

Purification and characterization of serine acetyltransferases truncated at C-terminal regions.

Hiraoka Kenji, Mino Koshiki, Imamura Koreyoshi, Sakiyama Takaharu, Eisaki Naoki, Matsuyama Asahi, Nakanishi Kazuhiro, RITE

11 167 - 167 1999

Synthesis of β-pyrazole alanine using cysteine synthetase coupled with acetyl-CoA regeneration system.

Ohno Katsuhiro, Mino Koshiki, Yamanoue Tsuyoshi, Imamura Koreyoshi, Sakiyama Takaharu, Eisaki Naoki, Matsuyama Asahi, Nakanishi Kazuhiro, RITE

11 184 - 184 1999

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