• 한국식품영양학회지
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• 제7권3호
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• pp.177-182
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• 1994

The effect of phosphate salt (NafHP04) and sodium citrate on the emulsion stability of soy protein isolate (SPI) in the presence of calcium was investigated in terms of salt concentration and addition order. Both phosphate and citrate salts decreased the solubility of SPI despite their pH enhancing effects. Addition of calcium chloride (CaCl2) significantly decreased ES, which showed nearly negligible at more than 3 mM CaCl2 concentration. When Na2HP04 were added in the presence of 5 mM Cac12, 55 greatly increased up to 20mM concentration, above which however ES decreased. It was found that the addition order of Na2HPO4 and CaCl2 affected ES. The addition of phosphate and subsequent CaCl2 exhibited the higher 55 than the reverse order. In both cases, the overall ES profile was found to be nearly similar to the solubility profile of SPI, indicating the positive relationship between solubility and emulsion stability of SPI in the presence of calcium. Similar trend to the phosphate effect on ES was also observed for sodium citrate in the presence of calcium.

• 대한가정학회지
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• 제28권4호
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• pp.41-50
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• 1990

Soy protein was isolated from Korean soy bean 'Chang ryub' and chemically modified with succinic anhydride. Functionality of the soy protein isolate(SPI), succinylated SPI(SPPI), and PP590(commercial) at various pH were investigated. The mechanical and sensory properties of soy bean curds made from several mixing ratio of succinylated soy bean milk were observed. The solubility of SPI significantly increased with succinylation. The solubility of PP590 was lower than that of SSPI. The solubility of SPPI increased significantly in 0.03M CaCl2 solution. The emulsifying activity of SSPI increased. On the range of pH above pI the emulsifying activity of PP590 was higher than that of SPI. There was no difference in emulsion stability among the groups. The foam expansion capacity of SPPI increased at higher pH than pI but the foam stability decreased significantly above pH 9. Mechanical texture profile analysis revealed the modified soy bean curds had the lower hardniss, chewiness and cohesiveness with increased modification. The mechanical characteristics of modified soy bean curds revealed generalized Maxwell Model of 7-elements or 5-elements. In sensory evaluation, the hardness, the springiness and acceptability of modified soy bean curds were lower significantly than those of control soy bean curd.

• 한국식품과학회지
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• 제22권4호
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• pp.386-392
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• 1990

장려품종 콩 19종의 단백질 특성 비교로 추출용매에 따른 단백질 획분의 분포, 전기영동 특성 및 아미노산 조성을 조사하였다. 이들 콩에 함유된 글리시닌은 콩단백질의 $48.19{\sim}58.86%$를 차지하였으며 다른 획분에 비해 프롤라민의 비율은 콩의 품종간에 큰 차이를 보였다. 콩 단백질의 전기영동 양상은 팔달, 장백, 장엽, 단엽, 남천 및 S-138이 $21.5{\sim}31.0kd$ 범위에서 보인 단백질 분리대의 차이를 제외하고서는 품종간의 차이가 없었다. 콩에 소량 함유된 아미노산류는 시스테인 메티오닌 티로신 및 트레오닌이었으며 티로신의 비율이 다른 아미노산에 비해 품종에 따른 차이가 가장 큰 것으로 나타났다.

• 한국식품과학회지
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• 제17권5호
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• pp.383-388
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• 1985

분리대두단백질을 succinic anhydride 및 acetic an-hydride와 반응시켜 화학적으로 변형시켜 기능성을 조사한 결과, 대두단백질의 등전점이 pH4.5에서 4.0으로 내려가면서 등전점이상의 영역. 특히 PH4.0-6.0영역에서 용해도가 크게 증가하였다. $Ca^{2+}$이 존재할 때 용해도는 변형시킨 경우 분리대두단백질에 비하여 4배 이상으로 증가하였다. 유화특성 및 기포특성 또한 크게 향상되는 결과를 보였다. 대두단백질의 고유점도를 측정한 결과 변형에 의하여 전반적으로 증가하였으며 희석용액으로부터 추정되는 입자간의 interaction coefficient는 감소하였다.

• Applied Biological Chemistry
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• 제31권4호
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• pp.382-386
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• 1988

Chemically defined medium을 사용하여 Bacillus sp. $T_2-3$으로 균체외단백질을 생산한 후 이들의 각종 물리화학적 성질을 조사 하였다. 균체외단백질은 전기영동과 gel 여과 결과로 분자량이 약 49,000이 되는 비슷한 2종의 단백질로 구성되어 있었다. 최대흡수파장은 230nm 부근이었으며 aspartic acid를 가장 많이 함유하고 있었다. 또한 균체외단백질의 물에대한 용해도는 55.8%, 0.4% NaOH에 대한 용해도는 28.4%로 albumin과 glutelin계통의 단백질로 생각되었다.

• 한국식품조리과학회지
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• 제20권3호
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• pp.256-264
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• 2004

The effects of irradiation on the functional and structural characteristics of soy protein isolates were studied. Soymilk was irradiated at 1, 5, and l0kGy, after which soy protein isolates were prepared. The functional properties of soy protein isolates were examined including solubility, emulsion capacity and stability, foam capacity and stability, structural properties as represented by SDS-PAGE pattern, and secondary and tertiary structures. The solubility and emulsion capacity were increased by radiation treatment at 1kGy however the values were adversely affected again as dosage was increased above 5kGy. As irradiation dosage increased, an increase of foaming capacity at 1kGy and a decreasing turnover afterwards were also noted in foaming capacity, although the differences were not statistically significant. The SDS-PAGE pattern showed fragmentation and aggregation of protein molecules as affected by irradiation in proportion to the dosage increase. The results of CD and fluorescence spectroscopy revealed increased aperiodic structure contents with the dosage increase. It was assumed that irradiation dosagefrom 5 to l0kGy could initiate minimal denaturation of protein in various foods compared to general heat treatment.

• 한국식품조리과학회지
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• 제9권1호
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• pp.43-51
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• 1993

Buckwheat protein isolate was tested for the effects of pH, addition of sodium chloride and heat treatment on solubility, emulsion capacities, emulsion stability, surface hydrophobicity, foam capacities and foam stability. The solubility of buckwheat protein isolate was affected by pH and showed the lowest value at pH 4.5, the isoelectric point of buckwheat protein isolate. The solubility significantly as the pH value reached closer to either ends of the pH, i.e., pH 1.0 and 11.0. The effects of NaCl concentration on solubility were as follows; at pH 2.0, the solubility significantly decreased when NaCl was added; at pH 4.5, it increased above 0.6 M; at pH 7.0 it increased; and at pH 9.0 it decreased. The solubility increased above $80^{\circ}C$, at all pH ranges. The emulsion capacity was the lowest at pH 4.5. It significantly increased as the pH approached higher acidic or alkalic regions. At pH 2.0, when NaCl was added, the emulsion capacity decreased, but it increased at pH 4.5 and showed the maximum value at pH 7.0 and 9.0 with 0.6 M and 0.8 M NaCl concentrations. Upon heating, the emulsion capacity decreased at acidic pH's but was maximised at pH 7.0 and 9.0 on $60^{\circ}C$ heat treatment. The emulsion stability was the lowest at pH 4.5 but increased with heat treatment. At acidic pH, the emulsion stability increased with the increase in NaCl concentration but decreased at pH 7.0 and 9.0. Generally, at other pH ranges, the emulsion stability was decreased with increased heating temperature. The surface hydrophobicity showed the highest value at pH 2.0 and the lowest value at pH 11.0. As NaCl concentrationed, the surface hydrophobicity decreased at acidic pH. The NaCl concentration had no significant effects on surface hydrophobicity at pH 7.0, 9.0 except for the highest value observed at 0.8 M and 0.4 M. At all pH ranges, the surface hydrophobicity was increased, when the temperature increased. The foam capacity decreased, with increased in pH value. At acidic pH, the foam capacity was decreased with the increased in NaCl concentration. The highest value was observed upon adding 0.2 M or 0.4 M NaCl at pH 7.0 and 9.0. Heat treatments of $60^{\circ}C$ and $40^{\circ}C$ showed the highest foam capacity values at pH 2.0 and 4.5, respectively. At pH 7.0 and 9.0, the foam capacity decreased with the increased in temperature. The foam stability was not significantly related to different pH values. The addition of 0.4 M NaCl at pH 2.0, 7.0 and 9.0 showed the highest stability and the addition of 1.0 M at pH 4.5 showed the lowest. The higher the heating temperature, the lower the foam stability at pH 2.0 and 9.0. However, the foam stability increased at pH 4.5 and 7.0 before reaching $80^{\circ}C$.

• 한국식품과학회지
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• 제31권3호
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• pp.658-664
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• 1999

GOD (glucose oxidase)나 제빵용 효모를 사용하여 포도당이 제거된 육계와 돼지 혈장분의 상온 저장중 색깔, biuret 단백질 함량, 용해도, 기포력과 pH의 변화를 조사하였다. 혈장분의 종류와 혈당 제거 법과는 상관없이 실험기간 동안 혈당이 제거된 혈장분은 해당 대조구보다 "L" 값이 같거나 높았으며 "a" 값과 "b"값은 낮았다(P<0.05). 축종 또는 혈당 제거 방법과는 상관없이 탈당된 모든 시료의 단백질 함량과 용해도는 상온 저장중 해당 대조구보다 항상 높았고 저장 기간이 경과할수록 감소하는 경향을 보였다(P<0.05). 대체적으로 탈당된 육계와 돼지 혈장분 기포력은 해당 대조구와 비슷하거나 높았다. 그러나 돼지 혈장분의 기포력은 육계 혈장분과는 다르게 실험기간 동안 탈당된 돼지 혈장분과 상응하는 대조구는 큰 차이를 나타내지 않았다(P<0.05). 육계 대조구와 GOD로 혈장 포도당을 제거한 육계 혈장분의 pH는 저장기간이 지남에 따라 감소하였지만 효모로 포도당을 제거한 육계 혈장분과 모든 돼지 시료의 pH는 실험 기간중 증가하였다가 감소하였다. GOD로 포도당을 제거한 육계 혈장분이 해당 육계 시료 보다 낮은 pH값을 보인 반면 돼지 혈장분에서는 대조구가 상응하는 실험구보다 항상 낮은 pH 값을 나타내었다(P<0.05). 육계와 돼지 혈장의 포도당을 제거한 후 혈장을 건조시키면 혈장분의 색깔, biuret 단백질 함량, 용해도 그리고 기포력을 증진시킬 수 있었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제3권1호
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• pp.35-39
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• 1998

An enzymatic process was developed to produce protein hydrolysater form defatted soya protein. Various unit operations were tried, and the effects of pre- and post-treatments on the product characteristics such as degree of hydroylsis (DH), free amino acid content (%FAA) and average molecular weight (MW) were investigated. The use of acid washes showed no difference in %DH. Increasing pH during pre-cooking gave lower %DH. Alkaline cooking made too much insoluble protein, thus the protein yield was too small. A better hydrolysis with more acceptable taste was obtained when the combination of Neutrase/Alcalase/Flavourzyme was used in place of Alcalase/Flavourzyme combination; Untoasted defatted soya was more effective on the proteolysis than toasted one. The MW of the evaporated and spray dried product was higher than that of undried product, due to precipitation of low-solubility components. When ultrafiltration and the product concentration carried out the product separation by reverse osmosis, the solubility and the taste of the product were improved. The difference between enzyme hydrolysate and acid hydrolysate was significant in free amino acid composition, especially in tyrosine, phenylalanine, glutamine and asparagine.

• 한국자기공명학회논문지
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• 제17권1호
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• pp.30-39
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• 2013

Immortalization-upregulated protein-1 (IMUP-1) genes have been cloned and are known to be involved in SV40-mediated immortalization. IMUP-1 gene is highly expressed in various cancer cell lines and tumors, suggesting the possibility that they might be involved in tumorigenicity. Previously, there were several problems for overexpression of IMUP-1 in bacterial expression systems including low solubility and aggregation due to unstructured property. To investigate the structural properties, it is necessary to obtain lots of pure and soluble proteins. Accordingly, the co-expression systems of bacterial chaperone proteins, GroEL-GroES, were used to increase solubility of IMUP-1. From the analysis of NMR and CD experiment data, it is suggested that the protein adopt typical the random coil properties in solution.