Faculty Profiles - IMAMURA Koreyoshi

MISC - IMAMURA Koreyoshi

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Effects of types of sugar on the stabilization of protein in the dried state

K Imamura, T Ogawa, T Sakiyama, K Nakanishi

JOURNAL OF PHARMACEUTICAL SCIENCES 92 ( 2 ) 266 - 274 2003.2

Language：English Publisher：JOHN WILEY & SONS INC

The effects of various sugars on the structural stabilization of protein during freeze-drying were investigated. The degree of native structure of protein that was freeze-dried and rehumidified at constant relative humidities (RHs) was evaluated by measurement of the alpha-helix content by Fourier-transform infrared spectroscopy. Bovine serum albumin (BSA) and several types of sugars, including sucrose, trehalose, and dextrans, were used as a model protein and sugars, respectively. The glass transition temperature, T-g for the amorphous sugar samples was measured by differential scanning calorimetry (DSC) to characterize the structural stability of sugars. The dependence of the alpha-helix content (Calpha-helix) of BSA on the sugar content (c(sugar)) could, in most cases, be represented by a Langmuir-type equation: Calpha-helix = K x (C-alpha-helix(max)-C-alpha-jelix(0)) x c(sugar)/(1 + K x c(sugar)) + C-alpha-helix(0), where K is a constant, indicating the ability of amorphous sugar matrix to embed protein, and C-alpha-helix(0) and C-alpha-helix(max) indicate the alpha-helix content in the absence of sugar and saturating levels of sugar, respectively. The preservation effects of the sugars could be characterized by K and C-alpha-helix(max). Both K and C-alpha-helix(max) values tended to be higher with decreasing T-g values for the amorphous sugar, probably because an amorphous sugar matrix with lower T-g values is structurally more flexible. The rehumidification of protein that was freeze-dried in the presence of sugar induced the refolding of protein structure, whereas the protein dried alone did not show any recovery of its native structure. (C) 2003 Wiley-Liss, Inc.

DOI： 10.1002/jps.10305

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Effects of types of sugar on the stabilization of protein in the dried state

K Imamura, T Ogawa, T Sakiyama, K Nakanishi

JOURNAL OF PHARMACEUTICAL SCIENCES 92 ( 2 ) 266 - 274 2003.2

Language：English Publisher：JOHN WILEY & SONS INC

DOI： 10.1002/jps.10305

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Ionization characteristics of polyelectrolyte complex gels: analysis based on their swelling behaviors

T. Sakiyama, T. Tsutsui, E. Masuda, K. Imamura, K. Nakanishi

Macromolecules 36 ( 13 ) 5039 - 5042 2003

ペプチドのステンレス表面への吸着に対する酸性アミノ酸残基の寄与

Journal of Colloid and Interface Science 276 ( 2 ) 294 - 301 2003

ステンレス表面に吸着したタンパク質のH₂O₂－電気分解による脱離の速度論と処理効果に及ぼす諸因子の影響

Journal of Colloid and Interface Science 265 ( 1 ) 49 - 55 2003

酵素法による脂質付加食品素材物質の大量合成法の開発と機能性の解明

中西一弘, 今村維克, 安達修二

年報 2003 271 - 277 2003

In situ analysis of the removal behavior of protein adsorbed on a titanium surface by H2O2-electrolysis treatment

K Imamura, T Sakiyama, K Nakanishi

LANGMUIR 18 ( 21 ) 8033 - 8039 2002.10

Language：English Publisher：AMER CHEMICAL SOC

The kinetics of the removal of beta-lactoglobulin (beta-Lg) adsorbed to a titanium surface using a method involving the electrolysis of hydrogen peroxide (H2O2)-electrolysis treatment) was examined. The rate of decrease in the thickness of the layer of beta-Lg adsorbed to the titanium surface during the H2O2-electrolysis treatment was measured in situ by ellipsometry, The rate for this process followed first-order reaction kinetics. Relationships between the rate constant for removal and such factors as the H2O2 concentration, the potential applied to the titanium surface, the supporting electrolyte concentration, and temperature were experimentally studied. The rate of removal of the adsorbed beta-Lg from a stainless steel surface was found to be much slower than that from a titanium surface, indicating that the type of metal also affects the removal characteristics during the H2O2-electrolysis treatment.

DOI： 10.1021/la025893i

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In situ analysis of the removal behavior of protein adsorbed on a titanium surface by H2O2-electrolysis treatment

K Imamura, T Sakiyama, K Nakanishi

LANGMUIR 18 ( 21 ) 8033 - 8039 2002.10

Language：English Publisher：AMER CHEMICAL SOC

DOI： 10.1021/la025893i

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Water sorption and glass transition behaviors of freeze-dried sucrose-dextran mixtures

K Imamura, A Fukushima, K Sakaura, T Sugita, T Sakiyama, K Nakanishi

JOURNAL OF PHARMACEUTICAL SCIENCES 91 ( 10 ) 2175 - 2181 2002.10

Language：English Publisher：JOHN WILEY & SONS INC

The water sorption and glass transition behaviors of freeze-dried disaccharide-polysaccharide mixtures at various contents were investigated at relative humidities (RHs) of 0, 11, 23, and 33%. Sucrose and three types of dextrans, which differ in molecular weight, were used as model di- and polysaccharides, respectively. The relationship between the dextran and water contents of the sucrose-dextran mixture at different constant RHs indicated that a mixture of sucrose and dextran was lower than that calculated by the Lang and Steinberg mass balance equation. In the RH range of 0-23%, the glass transition temperature, T-g, increased to a considerable extent when the dextran content was equal to or higher than 50%, while the increase in T-g, at dextran contents lower than 50% was small. A marked increase in T-g, was observed at RH 33% for dextran contents of 0-25% as well as in the range above 50%. This suggests that the physical stability of the highly hydrated amorphous disaccharide is effectively strengthened by the addition of a small amount of polysaccharide. These tendencies were similar for the three dextrans of different molecular weights. Furthermore, it was demonstrated that the addition of a small amount of dextran is quite effective in preventing the collapse of amorphous sugar during freeze drying. (C) 2002 Wiley-Liss, Inc.

DOI： 10.1002/jps.10218

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A Novel Cleaning Method Using Electrolysis of Hydrogen Peroxide

IMAMURA Koreyoshi, NAKANISHI Kazuhiro

77 ( 899 ) 800 - 805 2002.9

粉末系におけるゼインの二次構造に及ぼす水分活性と脂質添加の影響

MIZUTANI YUKIKO, MATSUMURA YASUO, IMAMURA TADAKATSU, NAKANISHI KAZUHIRO, MORI TOMOHIKO

日本食品科学工学会大会講演集 49th 152 2002.8

Removal of proteinaceous soils using hydroxyl radicals generated by the electrolysis of hydrogen peroxide

K Imamura, Y Tada, H Tanaka, T Sakiyama, K Nakanishi

JOURNAL OF COLLOID AND INTERFACE SCIENCE 250 ( 2 ) 409 - 414 2002.6

Language：English Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

We have developed here for the first time a novel method to generate hydroxyl radicals, .OH, by applying slightly negative electric potentials (-0.2 - -0.8 V vs Ag/AgCl) to the surface of a metal (or metal oxide) that is in contact with hydrogen peroxide solution containing a supporting electrolyte. Namely, .OH radicals were generated at the surface by the electrolysis of hydrogen peroxide according to the equation, H2O2 + e(-) --> .OH + OH-. This method was used to clean a stainless steel fouled with a model protein, beta-lactoglobulin. The .OHs generated at the surface were effective in removing beta-lactoglobulin that had been irreversibly adsorbed, by several minutes of treatment at room temperature (22 +/- 2degreesC). The removal rates measured for various concentrations of H2O2, and supporting electrolyte and different potentials were determined exclusively by the electric current. (C) 2002 Elsevier Science (USA).

DOI： 10.1006/jcis.2002.8368

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Removal of proteinaceous soils using hydroxyl radicals generated by the electrolysis of hydrogen peroxide

K Imamura, Y Tada, H Tanaka, T Sakiyama, K Nakanishi

JOURNAL OF COLLOID AND INTERFACE SCIENCE 250 ( 2 ) 409 - 414 2002.6

Language：English Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

DOI： 10.1006/jcis.2002.8368

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食品製造プロセスで発生する汚れの新規洗浄方法 (特集:食品製造装置の洗浄殺菌)

中西一弘, 崎山高明, 今村維克

食品工業 45 ( 2 ) 18 - 24 2002.1

Adsorption behavior of methylene blue and its congeners on a stainless steel surface

K Imamura, E Ikeda, T Nagayasu, T Sakiyama, K Nakanishi

JOURNAL OF COLLOID AND INTERFACE SCIENCE 245 ( 1 ) 50 - 57 2002.1

Language：English Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

Methylene blue and its congeners as model dyes were adsorbed onto stainless steel particles at different ionic strengths, pH values, and ethanol contents, and the adsorption mechanism was investigated. A Fourier transform infrared spectroscopy (FTIR) analysis of the dyes adsorbed on the stainless steel plate was carried out to determine the orientations of the adsorbed dyes on stainless steel surface. The adsorption isotherms for all the dyes tested were approximated by a Langmuir equation (Q = K q(m) C/(1 + KC)) in most cases except under strongly basic conditions. From the ionic strength and ethanol content dependencies of the K value in the Langmuir equations, both the electrostatic and hydrophobic interactions were indicated to contribute to the adsorption of the dyes at neutral pH. By comparing the K and q(m) values for the methylene blue congeners and with the aid of the FTIR analyses, it was found that the kind of substituent groups at most positions of the polyheterocycles of methylene blue strongly affects the adsorption behavior, particularly the area occupied by an adsorbed dye molecule, the affinity for the stainless steel surface, and the orientation of the adsorbed dye molecule on the stainless steel surface. (C) 2002 Elsevier Science.

DOI： 10.1006/jcis.2001.7967

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Adsorption behavior of methylene blue and its congeners on a stainless steel surface

K Imamura, E Ikeda, T Nagayasu, T Sakiyama, K Nakanishi

JOURNAL OF COLLOID AND INTERFACE SCIENCE 245 ( 1 ) 50 - 57 2002.1

Language：English Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

DOI： 10.1006/jcis.2001.7967

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Influences of the Suspension Method of Thermolysin in Organic Solvents on Enzyme Activity

Keizo Tanaka, Koreyoshi Imamura, Takaharu SAkiyama, Kazuhiro Nakanishi

Japan Journal of Food Engineering 3 ( 1 ) 15 - 23 2002

Language：English Publisher：日本食品工学会

Thermolysin (EC 3. 4. 24. 4) was suspended in organic solvents containing a small amount of water (aqueous buffer solution) by two different methods, and the catalytic activity as well as the conformational changes in the enzyme were compared. In one method (Method 1), dried powder enzyme was directly suspended in organic solvents containing a small amount of water while in the second method (Method 2), the dried enzyme was first dissolved in the buffer solution and then added to the anhydrous organic solvents containing the same final water content as that used in Method 1. In Method 2, the enzymes showed a catalytic activity 2-10 times as high as that in Method 1. The ratio of the activity obtained in Method 2 to that in Method 1 strongly depended on kinds of organic solvents, and its dependency was reasonably explained by the ET(30) values, which represent the extent of polarity of an organic solvent. The Fourier transform infrared spectroscopy (FT-IR) analyses indicated that the enzyme conformation in Method 2 was closer to its native one than that in Method 1. The influences of the suspension method on the enzyme activities of the different forms of the enzyme (as donated, dialyzed, and cross-linked) and the courses of the enzyme activities during incubation in Methods 1 and 2 were also investigated. © 2002, Japan Society for Food Engineering. All rights reserved.

DOI： 10.11301/jsfe2000.3.15

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Water sorption and glass transition behaviors of freeze-dried sucrose-dextran mixtures

Koreyoshi Imamura, Atsushi Fukushima, Keisuke Sakaura, Takuo Sugita, Takaharu Sakiyama, Kazuhiro Nakanishi

Journal of Pharmaceutical Sciences 91 ( 10 ) 2175 - 2181 2002

Language：English Publisher：John Wiley and Sons Inc.

The water sorption and glass transition behaviors of freeze-dried disaccharide-polysaccharide mixtures at various contents were investigated at relative humidities (RHs) of 0, 11, 23, and 33%. Sucrose and three types of dextrans, which differ in molecular weight, were used as model di- and polysaccharides, respectively. The relationship between the dextran and water contents of the sucrose-dextran mixture at different constant RHs indicated that a mixture of sucrose and dextran was lower than that calculated by the Lang and Steinberg mass balance equation. In the RH range of 0-23%, the glass transition temperature, Tg, increased to a considerable extent when the dextran content was equal to or higher than 50%, while the increase in Tg at dextran contents lower than 50% was small. A marked increase in Tg was observed at RH 33% for dextran contents of 0-25% as well as in the range above 50%. This suggests that the physical stability of the highly hydrated amorphous disaccharide is effectively strengthened by the addition of a small amount of polysaccharide. These tendencies were similar for the three dextrans of different molecular weights. Furthermore, it was demonstrated that the addition of a small amount of dextran is quite effective in preventing the collapse of amorphous sugar during freeze drying. © 2002 Wiley-Liss, Inc.

DOI： 10.1002/jps.10218

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S219 Prospects for micro-bioreactor systems with respect to reactor and biocatalyst designs

Nakanishi Kazuhiro, Sakiyama Takaharu, Imamura Koreyoshi

14 21 - 21 2002

308 Analysis and control of adsorption behavior of enzyme onto a solid surface

Ohnishi Kousuke, Imamura Koreyoshi, Sakiyama Takaharu, Nakanishi Kazuhiro

14 28 - 28 2002

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