• 미생물과산업
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• 제12권1호
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• pp.9-14
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• 1986

We have adopted a genetic approach to identifying those residues and local sequences in a polypeptide chain which play an important role on the folding pathway. Our approach has been to isolate and characterize mutants which specifically alter the folding and subunit association pathway of a polypeptide chain, without altering the native protein. Such mutants distinguish residues involved in the kinetic control of conformation from residues involved in the stability and activity of the native protein. This approach is complementary to the efforts to characterize mutations which alter the stability of the mature protein(6,7,8). It is likely that many residues will have roles in both aspects of the functioning of the polypeptide chain. We thought it likely, however, that at least with large proteins, these aspects might be segregated in different local sequences.

• 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 $80^{\circ}C$.

• Applied Biological Chemistry
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• 제36권3호
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• pp.172-177
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• 1993

참깨박에 함유되어 있는 불용성 형태의 단백질을 Bacillus sp. CW-1121이 생성하는 효소를 이용하여 가용성 형태의 단백질로 용출시키기 위하여 효소를 작용시켰다. 효소 처리 참깨박 단백질의 기포 형성력은 염용성 단백질이 수용성 단백질에 비해 현저히 낮았다. 기포 안정성은 염용성 단백질이 10분 이내 크게 감소된 반면 수용성 단백질의 기포 안정성은 30분 까지 완만하게 감소하였다. 유화력은 각 단백질의 등전점 부근에서 가장 낮았으며, 염용성 단백질이 수용성 단백질에 비해 낮았다 유화 안정성은 유화력과 비슷한 크기로 나타나 $80^{\circ}C$에서의 30분 가열에서도 이들 단백질이 열에 안정함을 보였다. 유지 및 수분 흡착력은 염용성 단백질이 수용성 단백질 보다 높은 값을 나타내었다.

• 한국축산식품학회지
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• 제23권1호
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• pp.63-69
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• 2003

본 연구는 단백질분해효소로 whey protein을 가수분해하여 얻은 가수분해물의 용해도와 유화특성의 변화를 측정하기 위해 실시하였다. Whey protein concentrates를 porcine trypsin(E : S=1 ; 3,000)으로 pH 8.0, 37$^{\circ}C$에서 6시간 동안 가수분해한 whey protein 가수분해물의 유화활성은 분해 4시간째에 가장 높게 나타났으며, 이 때 가수분해도는 5.50%이었다. whey protein의 효소가수분해로 whey protein 중의 $\alpha$-lactalbumin은 분해가 잘 일어나지 않으나 $\beta$-lactoglobulin은 분해 초기부터 급속히 분해되며 유화력 상승에 관여하는 여 러개의 저분자량 peptide를 생성하였다. 가수분해물의 용해도는 가수분해시간이 지남에 따라 증가세를 보이다가 5시간부터 조금씩 감소 추세를 보였으며, pH에 따라서는 등전점 부근인 pH4~5에서 용해도가 가장 낮았으나 가수분해시간이 증가함에 따라 이 부근의 용해도가 현저히 증가하였으며 pH 6이상에서는 pH가 증가함에 따라 용해도도 증가하였다. 유화활성은 용해도의 결과와 거의 비슷한 결과를 나타내었다. 유화 안정성은 분해시간이 지남에 따라 조금씩 증가함을 보여주었으나, 가수분해 4시간부터 pH 8 이상의 PH에서 급격한 증자를 나타내었다.

• 한국식품영양과학회지
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• 제12권3호
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• pp.251-258
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• 1983

엽농축단백질(葉濃縮蛋白質)(LPC)을 이용해서 인공유(人工乳)를 만들 수 있는 기틀을 마련코저, 엽농축단백질(葉濃縮蛋白質)의 기능적(機能的) 성질(性質)을 milk casein 수준으로 높이기 위해 섬바디(Dystaenia takeshimana Nakai) 잎에서 추출한 chloroplastic protein과 cytoplasmic protein 및 Italian ryegrass(Lolium multiflorum Lamb.)에서 추출(抽出)한 엽농축단백질(葉濃縮蛋白質) 1g당 succinic anhydride 0. 10, 0. 25, 100g씩을 가(加)해 숙시닐화시켜 기능성을 조사한 결과는 다음과 같다. 1. bulk density는 섬바디잎에서 추출한 chloroplastic protein 및 cytoplasmic protein과 Italian ryegrass에서 추출한 LPC가 succinic anhydride의 무처리구에서 높았으며 숙시닐화 시킴으로 감소한 후 숙시닐화가 증가하므로서 bulk density는 어느 정도 증가하는 추세였다. 2. 용해도는 숙시닐화를 시킨 각 구에서는 Italian ryegrass LPC 1g에 succinic anhydride 1g 첨가반응시 섬바디 chloroplastic protein에서는 시료 1g당 succinic anhydride 0.1g이상 첨가반응시 milk casein 보다 용해도가 높은 경향이었다. 3. 흡수도 및 지방흡착에서는 숙시닐화 시킨 것과 시키지 않은 것 모두가 milk casein 보다 높은 경향이었다. 4. 유화능과 유제의 안정성에서는 숙시닐화를 시키지 않은 각(各) LPC가 약간 낮은 반면 숙시닐화 시킴에 따라 milk casein 보다도 높고 점점 증가하는 경향이었다.

• 한국식품과학회지
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• 제37권3호
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• pp.345-351
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• 2005

본 연구에서는 시판되고 있는 카제인 나트륨, 유청 단백질, 탈지분유 및 전지분유에 TGase를 첨가하여 이화학적 특성 및 식품첨가물 소재로서의 기능적 특성 등을 조사하였다. 카제인 나트륨의 경우 TGase효소 반응 후 pH 2, pH 4와 알칼리 범위에서, 유청 단백질은 pH 4에서 용해성이 향상되었고 탈지분유에서는 pH 4와 전지분유에서는 모든 pH 범위에서 용해성이 향상되었다. TGase를 첨가한 우유 단백질과 우유 분말 제품이 무첨가군에 비하여 pH 의존적으로 용해성, 유화활성 및 거품형성 등에 기능적 특성이 부분적으로 우수함을 알 수 있었다. 또한 TGase 첨가에 따라 일반성분의 변화가 없었으며 인체내 소화효소에 의해 가수분해가 용이하였고 점도의 증가가 관찰되었다. TGase를 첨가한 제품은 이화학적, pH 및 반응시간 등의 특징에 의하여 영향을 받으므로 식품에 응용할 경우 기능성들이 합리적으로 조절되도록 함이 바람직하다.

• 한국자기공명학회논문지
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• 제26권4호
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• pp.66-70
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• 2022

Protein structure determination using NMR spectroscopy requires a suite of heteronuclear 3-D NMR experiments that can take a couple of weeks for completion. During the experiments, protein samples may suffer from slow degradation due to co-purifying proteases, which complicates and slows down the assignment procedure. Here we describe a practical protocol to avoid unwanted proteolysis during the experiment.

• Asian-Australasian Journal of Animal Sciences
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• 제33권4호
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• pp.556-567
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• 2020

Objective: To improve the utility of native grass resources as feed in China, we investigated the dynamics of protein and carbohydrate fractions among Inner Mongolian native grasses, during ensiling and the aerobic stage, using the Cornell Net Carbohydrate and Protein System. Methods: Silages were prepared without or with lactic acid bacteria (LAB) inoculant. We analyzed the protein and carbohydrate fractions and fermentation quality of silages at 0, 5, 15, 20, 30, and 60 d of ensiling, and the stability at 0.5, 2, 5, and 10 d during the aerobic stage. Results: Inner Mongolian native grass contained 10.8% crude protein (CP) and 3.6% water-soluble carbohydrates (WSC) on a dry matter basis. During ensiling, pH and CP and WSC content decreased (p<0.05), whereas lactic acid and ammonia nitrogen (N) content increased (p<0.05). Non-protein N (PA) content increased significantly, whereas rapidly degraded true protein (PB₁), intermediately degraded true protein (PB₂), total carbohydrate (CHO), sugars (CA), starch (CB₁), and degradable cell wall carbohydrate (CB₂) content decreased during ensiling (p<0.05). At 30 d of ensiling, control and LAB-treated silages were well preserved and had lower pH (<4.2) and ammonia-N content (<0.4 g/kg of fresh matter [FM]) and higher lactic acid content (>1.0% of FM). During the aerobic stage, CP, extract ether, WSC, lactic acid, acetic acid, PB₁, PB₂, true protein degraded slowly (PB₃), CHO, CA, CB₁, and CB₂ content decreased significantly in all silages, whereas pH, ammonia-N, PA, and bound true protein (PC) content increased significantly. Conclusion: Control and LAB-treated silages produced similar results in terms of fermentation quality, aerobic stability, and protein and carbohydrate fractions. Inner Mongolian native grass produced good silage, nutrients were preserved during ensiling and protein and carbohydrate losses largely occurred during the aerobic stage.

• 한국식품영양과학회지
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• 제18권4호
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• pp.410-422
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• 1989

숙시닐화 또는 트립신처리에 의한 대두단백질분리물의 화학적 변형은 단백질의 함량을 감소시키는 것으로 나타났고, 아미노산 조성에서 tyrosine의 증가가 현저하였으나 lysine은 트립신처리시에만 크게 증가하였다. 화학적 변형은 단백질의 용해성을 증가시키고 pH의존성이 뚜렷하여 등전점 변이시키는 효과를 나타내었다. 단백질의 용해성은 염류의 농도증가에 의해 감소하는 경향을 나타내었으며, 화학적 변형은 유흡수성과 수분흡수성, 유화특성 및 기포성 등을 증가시키는 반면에 기포안정성을 다소 저하시키고 자외선흡광도와 용적밀도를 감소시켰다. 한편 대두단백질 분리물과 우육단백질의 혼합에 따른 상호작용에 의해서는 유화활성, 유화활성지수 및 기포성의 증가를 가져봤으나 유화안정성에 대해서는 현저한 효과가 나타나지 않았다.

• 한국식품조리과학회지
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• 제9권4호
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• pp.308-311
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• 1993

This study was carried out in order to study the effect of mungbean protein on quality characteristics of angel parfait. The foaming properties of mungbean protein was tested and angel parfait was made with mungbean protein. The results were as follows: 1. Foam expansion values of mungbean protein were generally dependent on protein concentration to 3かio protein suspension. From 1％ to 3％ suspen-sion, foam expansion values increased. However, over 3％ suspension, the values decreased. 2. The foaming stability appeared the greatest value as protein concentration increased. But it was not signifi-cantly different over than 5% concentration. 3. The overrun of angel parfait made with munbean protein was significantly higher than that of made with soybean protein and sensory evaluation data presented that angel parfait made with mungbean protein was significantly higher than that of soybean protein.