• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1628-1634
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• 2009

Small heat shock proteins (sHSPs) function as molecular chaperones that protect cells against environmental stresses. In the present study, the genes of hsp17.6 and hsp17.7, cytosolic class I sHSPs, were cloned from a tropical plant, Ageratina adenophorum. Their C-terminal domains were highly conserved with those of sHSPs from other plants, indicating the importance of the C-terminal domains for the structure and activity of sHSPs. The recombinant HSP17.6 and HSP17.7 were applied to determine their chaperone function. In vitro, HSP17.6 and HSP17.7 actively participated in the refolding of the model substrate citrate synthase (CS) and effectively prevented the thermal aggregation of CS at $45^{\circ}C$ and the irreversible inactivation of CS at $38^{\circ}C$ at stoichiometric levels. The prior presence of HSP17.7 was assumed to suppress the thermal aggregation of the model substrate CS. Therefore, this report confirms the chaperone activity of HSP17.6 and HSP17.7 and their potential as a protectant for active proteins.

• 대한공업교육학회지
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• 제33권1호
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• pp.249-264
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• 2008

본 연구에서는 저 에너지 이온 주입과 이중 열처리를 통하여 박막 $p^+-n$ 접합을 형성하였고, 보론 확산 모델을 가지고 새로운 시뮬레이터를 설계하여 이온 주입과 열처리 후의 보론 분포를 재현하였다. $BF_2$ 이온을 가지고 실리콘 기판에 저 에너지 이온 주입을 하였고, 이후 RTA(Rapid Thermal Annealing)와 FA(Furnace Annealing)를 통하여 열처리 과정을 수행하였다. 시뮬레이션을 위한 확산 모델은 점결함의 생성과 재결합, BI 쌍의 생성, 보론의 활성화와 침전 현상 등을 고려하였다. FA+RTA 열처리가 RTA+FA 보다 면저항 측면의 접합 특성에서 우수한 결과를 나타내었고, 시뮬레이터에서도 동일한 결과를 나타내었다. 따라서 본 연구를 통하여 박막접합을 형성할 때 열적 효율성을 고려하면 제안된 확산 시뮬레이터와 FA+RTA 공정 방법의 유용성을 기대할 수 있다.

• Applied Biological Chemistry
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• 제30권3호
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• pp.278-284
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• 1987

사과의 건조, 가공 중의 갈변을 방지하기 위한 기초 조사로서 후지 사과로부터 추출한 crude polyphenol oxidase의 특성과 열에 대한 저항성, 갈변 저해제의 저해 효과 등을 조사하였다. Catechol을 기질로 사용하였을 때 polyphenol oxidase의 최적 pH는 5.5, 최적온도는 $20^{\circ}C$, $K_m$ 값은 0.14M이었고, 열불활성화는 유사일차반응을 보였으며 이때 활성화에너지$(E_a)$와 Z값은 각각 23.0cal/kmol, $19.7^{\circ}C$였다. 기질에 따른 친화력은 o-diphenol, 특히 chlorogenic acid에 대하여 높았고, monophenol과 m-diphenol, p-diphenol에 대해서는 나타나지 않았다. Polyphenol oxidase에 의한 갈변은 thiourea와 potassium metabisulfite는 10mM에서, L-cysteine과 ascorbic acid, sodium diethyldithiocarbamate는 1mM에서 현저하게 저해되었다.

• 한국축산식품학회지
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• 제32권5호
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• pp.561-570
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• 2012

The objective of this study was to evaluate the effects of an atmospheric pressure plasma (APP) jet on L. monocytogenes inactivation, quality characteristics, and genotoxicological safety of cooked egg white and yolk. APP treatment using He gas resulted in a 5 decimal reduction in the number of L. monocytogenes in cooked egg white, whereas that using $He+O_2$, $N_2$, and $N_2+O_2$ decreased the number further, and to undetectable levels. All treatments of cooked egg yolk resulted in undetectable levels of inoculated L. monocytogenes. There were no viable cells of total aerobic bacteria after APP treatment on day 0 while the control showed approximately 3-4 Log CFU/g. On day 7, the numbers of total aerobic bacteria had increased by approximately 3 log cycles in cooked egg white, but there were no viable cells in cooked egg yolk after 2 min of APP jet. APP treatment decreased the $L^*$-values of cooked egg white and yolk significantly on day 0. No significant sensory differences were found among the cooked egg white samples, whereas significant reductions in flavor, taste, and overall acceptability were found in cooked egg yolks treated with APP jets. SOS chromotest did not reveal the presence of genotoxic products following APP treatments of cooked egg white and yolk. Therefore, it can be concluded that APP jets can be used as a non-thermal means to enhance the safety and extend the shelf-life of cooked egg white and yolk.

• Food Science and Biotechnology
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• 제17권1호
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• pp.199-202
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• 2008

The effects of $\beta$-(1,6)-galactosyl trehalose trisaccharide ($\beta$-GT) that was preferentially produced by Escherichia coli $\beta$-galactosidase on cryo- and thermo-protections of protein were investigated with those of other sugars at the level of 8% (w/v). As compared to a control without sugar additive, $\beta$-GT effectively enhanced 32-54% of the cryoprotection of fish actomyosin against repeated freeze-thawing and frozen storage, and also 49% of the protection against thermal inactivation of pyrophosphatase, respectively. As a result, it was significantly more effective than sorbitol and trehalose in both cryoprotection and thermoprotection. Thus, $\beta$-GT would be possibly applied as a sugar substitute for cryo- and thermo-protective applications of food protein.

• 미생물학회지
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• 제24권2호
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• pp.161-167
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• 1986

Some of the physiological properties of Sp816 bacteriophage of Bacillus subtilis SNU816 were characterized. It could form plaques on either B. subtilis SNU816 or B. natto 8102, but not on any other bacillus strains investrgated. Its plaque morphology was circular with a diameter of less than 1.0mm and had a narrow halo surrounding the clear center. Its latent period was 34-36 min and had a burst size of 547. It was most stable at pH 6.0, and rapidly inactivated at $60^{\circ}C$ with a initial deaty rate of -0.216 $min^{-1}$. Host range, thermal inactivation rate at $60^{\circ}C$, pH stability, and UV sensitivity revealed that SP816 was quite different from any other phages investigated together but seemed to be rather related to B. natto phages.

• 미생물학회지
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• 제20권3호
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• pp.105-112
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• 1982

The strain of Aspergillus, 6368A, producing acid protease showing high activity was isolated from soil, as a result of wide research about mold group. This strain was identified as a species of Aspergillus tubingensis by the investigation of morphological characteristics. The change of the enzyme production under the various media and culture condition was also studied. The optimum pH and stability of crude acid protease are 2.5, 2.0~4.5 and the optimum temeprature and thermal inactivation waas shown $50^{\circ}C,\;55^{\circ}C$, respectively. From the result of the study on the effects of metal ions, it was found that $MnCl_2,\;CoCl_2,\;CuCl_2,\;SrCl_2,\;and\;NiCl_2$ slightly increased the enzyme activity, on the other hand $ZnCl_2,\;CaCl_2,\;MgCl_2,\;SLS,\;and\;KMnO_4$ decreased it.

• 미생물학회지
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• 제3권2호
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• pp.1-8
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• 1965

The potato viruses, as possible potato virus X(PVX), potato virus Y(PVY), potato virus S(PVS) are isolated from potato tuber, which collected from eleven areas (Table 1) in Korea. These viruses are isolated by single lesion isolation, Aphid transmission and inoculating methods through the many species of the different plants. The PVX is identified by host range, symptoms, physical properties, serological reaction and electron micrography. The other two viruses are identified by the first two methods mentioned above. The results of the above experiments are as follows. The total value of these viruses infection is 81%. The value of PVX infection is higher than the other two viruses. The properties of PVX are marked as local lesions on Comphrena globosa. The dilution end point is $10^{-6}$, the thermal inactivation point is $70^{\circ}C$ and the size of virus particles is around 13 x 60 $m\mu$.

• 한국식품영양과학회지
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• 제30권5호
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• pp.844-847
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• 2001

감자로부터 polyphenol oxidase를 추출하여 열안정성에 영향을 주는 요인을 식품의 제조공정에 유용한 정보를 제공하기 위해 연구를 하였다. 감자의 PPO는 pH 7.0에서 가장 안정하였고, 이 효소는 8$0^{\circ}C$에서 1분간의 열처리로 효소 활성이 70% 저해되었다. 감자 PPO의 열안정성은 sodium chloride의 첨가로 감소되었으며, 2-mercaptoethanol과 dithiothreitol과 같은 환원제의 첨가로 역시 효소활성이 저해되었다.

• 한국식품과학회지
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• 제24권4호
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• pp.371-375
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• 1992

Bacillus licheniformis가 분비하는 ${\alpha}-amylase$를 정제한 후 기질과 금속이온이 효소의 열안정성에 미치는 영향에 대하여 연구하였다. $Ca^{++}$ 이온 및 $B^{+++}$ 이온의 존재시에는 D-value가 7,880 sec 및 2,210 sec로 대조구에 비하여 높은 값을 보였으며 $Ca^{++}$ 이온과 $B^{+++}$ 이온이 동시에 존재할 때는 $D_{85}=24,000\;sec$로 상승효과를 보였다. $Ca^{++}$ 이온 존재시 열불활성화에 대한 활성화에너지 $({\Delta}H{\neq})$는 320.2 kJ/mol이고 $B^{+++}$ 이온의 경우에는 212.9 kJ/mol이었으며 대조구에서는 183.9 kJ/mol 이었다. 기질의 존재하에서는 ${\alpha}-amylase$는 높은 열안정성을 보였는데 30% 전분의 존재하에 $96^{\circ}C$, 30분 열처리한 결과 약 51%의 잔존역가를 검출하였으며 기질에 $Ca^{++}$ 이온을 첨가하였을 때에는 열안정성이 더욱 증가하였다.