• Journal of Photoscience
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• 제9권2호
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• pp.293-295
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• 2002

The structural stability of bacteriorhodopsin (bR) solubilized by Triton X-100 (TX-100) was studied by measuring the denaturation kinetics in the dark and under illumination, and compared with the structural stability of bR solubilized by octyl-${\beta}$-glucoside (OG). In the dark, bR solubilized by TX- 100 was more stable than bR solubilized by OG. Under illumination, bR solubilized by TX-100 showed light-induced denaturation in the same manner as bR solubilized by OG. These results in the dark well correlated with the experimental results of the visible CD band. Although solubilized bR in the TX-100 concentration range of 2-50 mM showed almost identical positive CD band and did not denature in the dark at 35$^{\circ}$C, the kinetic constant of the photobleaching increased with the increase of TX-100 concentration. These results suggested that photo-intermediates of solubilized bR are destabilized by TX-100 micelles.

• BMB Reports
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• 제35권5호
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• pp.472-475
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• 2002

Phaseolus vulgaris phytohemagglutinin L is a homotetrameric-leucoagglutinating seed lectin. Its three-dimensional structure shows similarity with other members of the legume lectin family. The tetrameric form of this lectin is pH dependent. Gel filtration results showed that the protein exists in its dimeric state at pH 2.5 and as a tetramer at pH 7.2. Contrary to earlier reports on legume lectins that possess canonical dimers, thermal denaturation studies show that the refolding of phytohemagglutinin L at neutral pH is irreversible. Differential scanning calorimetry (DSC) was used to study the denaturation of this lectin as a function of pH that ranged from 2.0 to 3.0. The lectin was found to be extremely thermostable with a transition temperature around $82^{\circ}C$ and above $100^{\circ}C$ at pH 2.5 and 7.2, respectively. The ratio of calorimetric to vant Hoff enthalpy could not be calculated because of its irreversible-folding behavior. However, from the DSC data, it was discovered that the protein remains in its compact-folded state, even at pH 2.3, with the onset of denaturation occurring at $60^{\circ}C$.

• 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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• 제18권3호
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• pp.209-215
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• 1998

Effects of protein concentration, ionic strength, pH, and temperature range on the heat-induced denaturation of salt soluble protein extracted from spent layer meat were investigated. Viscosity of salt soluble protein heated at 65$^{\circ}C$ for 30 min began to increase sharply above 7 mg/ml of breast protein concentration, and above 21 mg/ml of leg protein concentration, respectively. Both turbidity and viscosity showed the highest value in cooked protein solution with pH 6.0 and 1% NaCl. The turbidity of salt soluble protein started to increase continuously from 40$^{\circ}C$ to 80$^{\circ}C$. The viscosity increased rapidly from 45$^{\circ}C$ to 60$^{\circ}C$ in breast protein, and increased from 50$^{\circ}C$ to 55$^{\circ}C$ in leg protein, respectively, and then kept relatively constant. Breast protein had higher viscosity than leg protein during heat-induced gelation. Therefore, salt soluble protein from spent layer meat was associated with denatured protein (turbidity change) prior to gelation (viscosity change) during heating. Breast protein showed lower thermal transition temperature, and better gel formation than leg protein during heating.

• 한국식품영양학회지
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• 제7권4호
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• pp.345-352
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• 1994

High protein beverage of cow-soy milk was prepared by mixing the soymilk and commercial homogenized cow milk in the various ratios. Effect of heat treatment, pH and addition of calcium and sucrose was studied on the water-soluble nitrogen of cow-soy milk The heat-treated soymilk at 10$0^{\circ}C$ were centrifuged at the range of 830~29,900xg for 30 min and 11,200xg was found to be proper for determination of the degree of protein denaturation by centrifugal method. When soymilk was heated at 70~10$0^{\circ}C$ for 30~240 min, soluble nitrogen (QA SN) in supernatant of protein was decreased to 78.0~56.8% due to protein denaturation. Most of heat denaturation of protein was found to be occurred during Initial heating 10$0^{\circ}C$ for all mixed cow-soy milk. The sedimentation of SN was maximum at pH 4.0 In the range of pH 3~8. Addition of sucrose affected little on oASN while calcium addition reduced %SN significantly to approx. 55% for soymilk(100%). The effect of Ca was less as the ratio of cow milk increased.

• 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.

• 한국식품과학회지
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• 제21권2호
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• pp.173-179
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• 1989

본 연구는 도살직후 저장온도와 저장시간이 PSE이상 돈육의 단백질 변성에 미치는 영향을 DSC를 이용하여 육단백질의 열변성, 열에 대한 안정성과 근장단백질 용해성을 검토하였으며 그 결과를 요약하면 다음과 같다. 도살후 PSE육의 저장온도가 상승됨에 따라, 저장시간이 경과됨에 따라 DSC-thermodiagram의 myosin+sarcoplasmic protein의 변성이 나타나는 endotherm enthalpy가 감소하였다. 도살 후 $1{\sim}4$시간 동안 PSE육의 저장온도가 $20^{\circ}C$일 때 myosin+sarcoplasmic protein의 변성이 적었으나 $25^{\circ}C$ 이상일 때는 단백질 변성이 증가하였다. PSE육의 drip 손실은 도살 후 가능한 신속히 $2^{\circ}C$에 냉각시킨 육에서 최고를 나타냈다. 그러나 도살직후 수시간 동안 $32{\sim}38^{\circ}C$에 항온시킨 PSE육은 wateriness가 심하여 drip손실이 현저히 증가하였다. PSE육의 창백성은 도살직후 육온을 $20^{\circ}C$로 급속냉각함으로써 개선할 수 있었다. PSE육의 myosin+sarcoplasmic protein 의 변성이 심할 수록 발생하는 drip 양이 증가하였다.

• 한국안광학회지
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• 제20권2호
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• pp.237-246
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• 2015

목적: 본 연구는 안구에 존재하는 항산화효소인 superoxide dismutase(SOD)와 catalase(CAT)가 UV-B에 반복적으로 노출되었을 때 유발되는 구조변성 및 활성저하의 상관관계를 밝히며, 자외선 차단 RGP렌즈의 사용으로 효소의 변성과 활성저하가 효율적으로 차단되는가를 알아보기 위하여 수행되었다. 방법: SOD와 CAT의 표준품으로 각각의 효소용액을 제조하고 하루 30분, 1시간 및 2시간씩 312 nm의 UV-B에 1, 2, 3, 4 및 5일 동안 반복적으로 노출시켰다. 이 때 UV-B에 직접 노출시킨 항산화효소의 구조 및 활성변화를 자외선 차단기능이 있는 RGP렌즈로 UV-B를 차단시킨 경우와 비교하였다. UV-B 반복노출에 따른 SOD와 CAT의 구조변성은 전기영동분석으로 확인하였으며, 이들 효소활성은 분석키트를 이용하여 비색분석법으로 측정하였다. 결과: UV-B에 반복노출된 SOD는 일일 30분 조사조건으로 반복노출되었을 때에도 전기영동분석에서 효소다중화(polymerization)가 관찰되었으나 활성의 변화는 10% 이내로 나타났다. 반면 UV-B에 반복노출된 CAT은 전기영동 시 효소밴드크기나 진하기가 감소하여 구조변성이 나타났음을 확인할 수 있었으며, 반복노출시간이 긴 경우 CAT은 전기영동분석에서 효소밴드를 보임에도 불구하고 그 활성은 완전히 소실되었다. 또한 UV-B 조사로 인한 CAT의 변성은 63.7%의 UV-B 차단기능을 가진 RGP렌즈의 사용으로 어느 정도 억제되었으나 완전히 억제되는 것은 아니었다. 결론: 이상의 결과로 UV-B 반복노출에 따른 항산화효소의 구조변성은 그 종류에 따라 효소활성의 감소정도와 반드시 일치하는 것은 아님을 알 수 있었다. 따라서 자외선으로 인한 항산화효소의 손상을 막기 위하여서는 콘택트렌즈를 착용한 상태에서 자외선 노출시간을 최소화하거나, FDA Class I 차단제에 해당하는 UV 차단율을 가지는 콘택트렌즈를 착용 또는 이에 상응하는 UV차단율을 가지는 선글라스를 덧착용할 것을 권장한다.

• Journal of Photoscience
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• 제9권2호
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• pp.118-121
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• 2002

A state of bacteriorhodopsin at high temperature was studied by various spectral measurements. The stability measurements indicated that the onset temperature of the denaturation was 70$^{\circ}C$ in the dark and 60$^{\circ}C$ under illumination. The reactivity of hydroxylamine with the Schiff's base also significantly increased in the temperature range between 60 and 70$^{\circ}C$. A spectral band at about 470 nm appeared in the temperature range higher than 60$^{\circ}C$. The circular dichroism spectra in the visible region started to change from a bilobed exiton type to a positive band at about 60$^{\circ}C$, suggesting that the two-dimensional configuration of bacteriorhodopsin molecules changed from crystalline to amorphous. All the measurements suggested a new state between 60 and 70$^{\circ}C$ in which bacteriorhodopsin is stable only in the dark.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1628-1628
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• 2001

Near infrared (NIR) spectroscopy is a powerful technique for non-destructive analysis that can be obtained in a wide range of environments. Recently, NIR measurements have been utilized as probe for quantitative analysis in agricultural, industrial, and medical sciences. In addition, it is also possible to make practical application on NIR for molecular structural analysis. In this work, Fourier transform near infrared (FT-NIR) measurements were carried out to utilize extensively in the relative amounts of different secondary structures were employed, such as Iysozyme, concanavalin A, silk fibroin and so on. Several broad NIR bands due to the protein absorption were observed between 4000 and $5000\;^{-1}$. In order to obtain more structural information from these featureless bands, second derivative and Fourier-self-deconvolution procedures were performed. Significant band separation was observed near the feature at $4610\;^{-1}$ ,. Particularly the peak intensity at $4525\;^{-1}$ shows a characteristic change with thermal denaturation of fibroin. The structural information can be also obtained by mid-IR and CD spectral. Correlation of NIR spectra with protein structure is discussed.