• Molecules and Cells
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• 제26권1호
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• pp.61-66
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• 2008

Cyclic AMP receptor protein (CRP) is allosterically activated by cAMP and functions as a global transcription regulator in enteric bacteria. Structural information on CRP in the absence of cAMP (apo-CRP) is essential to fully understand its allosteric behavior. In this study we demonstrated interdomain interactions in apo-CRP, using a comparative thermodynamic approach to the intact protein and its isolated domains, which were prepared either by limited proteolysis or using recombinant DNA. Thermal denaturation of the intact apo-CRP, monitored by differential scanning calorimetry, revealed an apparently single cooperative transition with a slight asymmetry. Combined with circular dichroism and fluorescence analysis, the thermal denaturation of apo-CRP could be interpreted as a coupled process involving two individual transitions, each attributable to a structural domain. When isolated individually, both of the domains exhibited significantly altered thermal behavior, thus pointing to the existence of non-covalent interdomain interactions in the intact apo-CRP. These observations suggest that the allosteric conformational change of CRP upon binding to cAMP is achieved by perturbing or modifying pre-existing interdomain interactions. They also underline the effectiveness of a comparative approach using calorimetric and structural probes for studying the thermodynamics of a protein.

• 한국안광학회지
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• 제12권1호
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• pp.9-15
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• 2007

본 연구는 UV-A 노출에 의해 유발된 안구 내에 존재하는 단백질 효소 중의 하나인 ribonuclease A(RNase A)의 변성을 차단할 수 있는 안경렌즈의 적절한 UV-A 차단율을 알아보기 위해 수행하였다. RNase A를 1, 3, 6, 24, 48, 72, 96시간 동안 365 nm의 UV-A에 노출시켜 노출시간에 따른 단백질의 변성 정도를 아크릴 아미드 겔 전기영동법으로 확인하였다. 또한, 20%, 50%, 80%, 99% UV 차단 효과를 가진 안경렌즈로 UV-A를 차단하였을 때 RNase A의 변성이 억제될 수 있는 지를 알아보았다. RNase의 변성은 1시간 동안의 UV 노출에 의해서도 유발되었으며, UV-A 노출시간이 길어질수록 그 정도는 심해졌다. 1시간의 UV-A 노출에 의해 유발된 미세한 RNase A의 변성은 20% 정도의 UV-A 차단으로 충분히 예방될 수 있었다. UV-A를 3시간 동안 노출하였을 때는 50%이상의 UV-A 차단율을 가진 렌즈가 RNase A의 변성을 막을 수 있었다. 6시간 동안 UV-A에 노출되었을 때에는 99%의 렌즈로 차단하였을 때조차도 RNase A의 변성이 완벽하게 차단되지 못했다. 그러나 96시간 동안 UV-A에 노출되었을 때 나타나는 심각한 단백질의 변성이 99%의 UV-A 차단 렌즈를 사용하였을 경우 크게 감소하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제15권4호
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• pp.585-590
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• 2002

The effects of a high level of sucrose on the moisture content, water activity, protein denaturation and sensory properties in Chinese-style pork jerky were investigated. The pork jerky with different levels (0, 12, 15, 18 and 21%) of sucrose was prepared. Fifteen frozen boneless pork legs from different animals were used in this trial. Sucrose is a non-reducing disaccharides and would not undergo non-enzymatic browning. Some studies pointed out that sucrose might be hydrolyzed during freezing, dehydration and storage into glucose and fructose, and cause non-enzymatic browning in meat products. The results showed that moisture content and water activity of pork jerky decreased with increase of the level of sucrose. At the same time, shear value was increased due to the reduced moisture content and water activity by osmotic dehydration. However, a higher level of sucrose had a significantly negative effect on protein solubility and extractability of myosin heavy chain of pork jerky due to non-enzymatic browning. From the results of sensory panel tests, the pork jerky with 21% of sucrose seems to be more acceptable by the panelists in hardness, sweetness and overall acceptability.

• 한국축산식품학회지
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• 제20권2호
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• pp.146-151
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• 2000

The objective of this study was to investigate the characteristics on the thermal denaturation of free drip released from pork loin during chilled storage using DSC(differential scanning calorimetry). DSC thermogram of drip released from normal pork(NORD) was characterized by a minor peak and two major peaks with temperature maxima at $61.5^{\circ}C$, $71.7^{\circ}C$ (associated with sarcoplasmic proteins) and $84.3^{\circ}C$ (associated with protein-protein interaction and aggregation). In the denaturation temperature of drip released from PSE pork (PSED), the peak(Tmax) at $59.0^{\circ}C$ was reduced by $2.5^{\circ}C$. When the thermograms were divided into segments correponding to the three peaks, $\Delta$H2 was shown to be reduced by 10% in PSED as compared to NORD. With the decrease in the solubility of sarcoplasmic proteins in PSE muscle, there was a corresponding increase the drip loss during the storage.

• 한국축산식품학회지
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• 제21권3호
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• pp.265-271
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• 2001

We investigated changes of immunoglobulin G (IgG) concentrations by heating and drying condition. Also it is performed to group for commercial product by promoting of IgG preservation and reducing of protein denaturation. The result was that content of IgG in colostrum was higher than normal milk. Especially, IgG content of colostrum within 12 hrs after parturition was over 44.67mg/ml and it is 60 times of normal milk. IgG contents was reduced rapidly according as passage of the time. IgG content of the sample heating at 30min at 65$^{\circ}C$ was still a little higher that heating for 10sec at 72$^{\circ}C$. IgG denaturation of heat treatment at 100$^{\circ}C$ for 10sec was lower than at 85$^{\circ}C$ for 30min. We investigated the changes of IgG concentrations of kinds of market milk different with heating processing. This result showed that IgG denaturation ratio by ultra high temperature pasteurization (UHT) was higher than long time low temperature pasteurization (LTLT). On the other hands, IgG content by spray drying was 14.5mg/g and freezing drying was 10.8mg/g. It showed that denaturation of protein content by freezing drying was more than spray drying.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2001년도 Proceedings of 2001 International Symposium
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• pp.146-148
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• 2001

The objective of this study was to investigate the behavior of ribonuclease A (RNase) at the water/methylene chloride interface. It was aimed at better understanding the denaturation of proteins upon emulsification. RNase was vulnerable to the interface-induced aggregation reactions that led to formation of water-insoluble aggregates upon emulsification. Biochemical analyses demonstrated that intermolecular covalent linkages might have been involved in the aggregation reactions. The protein instability observed with emulsification was traced to consequences of protein adsorption and conformational rearrangements at the interface. These results indicated that emulsifying aqueous protein solutions in organic solvents should be handled with care, since emulsification could bring denaturation and aggregation to proteins.

• Food Science and Biotechnology
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• 제14권1호
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• pp.11-15
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• 2005

Dynamic shear moduli of isolated soy protein solutions upon heating were measured to monitor gelation. Onsets of gelation coincide with onset temperatures of denaturation in glycinin and ${\beta}$-conglycinin solutions, whereas in isolated soy proteins, onset of gelation was above denaturation temperature of ${\beta}$-conglycinin with storage modulus increasing in two steps. The first increase in storage modulus of isolated soy proteins occurred at about $78.5^{\circ}C$, while the second increase started at about $93^{\circ}C$. Gel properties of soy protein gels having different proportions of glycinin and ${\beta}$-conglycinin were measured by compression-decompression test. ${\beta}$-conglycinin was responsible for gel elasticity. Glycinin significantly increased hardness, toughness, and fracturability of gels at high heating temperature near $100^{\circ}C$. Results reveal texture of soy protein gels can be controlled by regulating ratio of glycinin to ${\beta}$-conglycinin and heating temperature.

• Fisheries and Aquatic Sciences
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• 제25권1호
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• pp.31-39
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• 2022

To clarify the factors influencing the physical properties of fish after heat treatments, we investigated changes in the properties of proteins in the dorsal ordinary and dark muscle of yellowtail (Seriola quinqueradiata) heated under different conditions commonly used for the purposes of food hygiene. High-temperature/short-time heating (85℃ for 90 s and 75℃ for 60 s) affected the protein solubility more than low-temperature/long-time heating (63℃ for 30 min). Sodium dodecyl sulphate-polyacrylamide gel electrophoresis and differential scanning calorimetry showed that low-temperature/long-time heating reduced the degree of actin denaturation in fish compared with that by other heating conditions. In addition, collagen solubility was enhanced with low-temperature/long-time heating. Therefore, these results suggest that differences in the degree of actin and collagen denaturation are responsible for the enhanced meat tenderness and diminished meat shrinkage, resulting from low-temperature/long-time heating.

• Applied Biological Chemistry
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• 제13권1호
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• pp.81-85
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• 1970

한국답토양십종(韓國畓土壤十種)을 시료(試料)로하여 유효인산정량(有動燐酸定量)에 적합한 화학적(化學的) 추출방법(油出方法)을 찾고저 A-value인(燐)-32 추적자법(追跡子淪)에 의한 유효인산정량치(有效燐酸定量値)를 표준으로 하여 시험한 결과 다음과 같은 결과(讀果)를 얻었다. 1 A·value는 Fe-P(인산철(燐酸鐵))와만 1%수준(水準)의 유의상관(有意相鬪)이 있으므로 답토양(畓土壤)의 유효인산(有刻燐酸)은 Fe·p계(系)에 의하여 지배(支配)되고 있다고 볼 수 있다. 2. 본(本) 실험(實驗)에 사용(使用)한 6개침출법(個浸出法)은 Fe-P와 상안(相關)이 없으므로 답토양유효인산정량법(容土壤有效燐酸定量法)으로 적합하지 않다. 3. 답토양유효인산(容土壤有效燐酸)에 적합한 침출법(浸出法)은 Fe-P계(系)의 환원강도(還元强度)를 측정(測定)할 수 있는 것이어야 하며 침출강도(浸出强度)는 평균(平均) 270 ppm 으로 추정(推定)된다. 4. Bray No. 2-p는 Lancaster-p, Spurway-p, Truog-p 및 (Ca+Al)-p와 5% 수준(水準) 이상(以上)에서 유의상관(有意相關)이 있고 Al-P는 Olsen-P 및 Lancaster-p와, Ca-p는 Spurway-p와 1% 수준(水準)에서 유의상관(有意相關)이 있다.

• 한국식품과학회지
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• 제2권2호
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• pp.49-55
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• 1970

대두단백육(textured soybean protein food)의 제조 과정에서 분리한 대두단백의 건조공정은 단백 gel의 성질과 보수력, 점성도 같은 단백질 특성에 영향을 미쳤다. 모델시스템의 실험에서 질소용해계수로 표시한 대두단백의 변성도는 분리대두단백 gel의 강도의 중요한 변수로 나타났다. gel strength는 질소용해계수가 43이었을 때 최대가 되었고 질소 용해계수가 그보다 증가할 때나 감소할 때는 gel strength가 감소되었다. 이러한 사실은 분리대두단백의 건조공정 중 적당한 단백의 변성은 단백육제조에 필요하며 그 이상의 높은 질소용해계수를 갖도록 할 필요는 없다.