• 한국식품과학회지
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• 제27권4호
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• pp.506-515
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• 1995

저온발효된 김치에서 분리되어 Leuconostoc mesenteroides subsp. mesenteroides, Leu. mesenteroides subsp. dextranicum, Leu. paramesenteroides, Leu. lactis, Lactobacillus bavaricus 및 Lac. homohiochii로 각각 동정된 저온성 젖산균 60주에 대하여 여러 조건에서의 배양특성들을 조사하였다. 모든 균주들이 $5^{\circ}C,\;10^{\circ}C$ 및 $37^{\circ}C$에서 증식하였고, $45^{\circ}C$에서는 증식하지 못하였다. 최적 증식 온도는 Leu. mesenteroides의 균주들은 $33{\sim}34^{\circ}C$이었고, Lactobacillus속의 균주들은 $34{\sim}36^{\circ}C$이었다. Leu. mesenteroides와 Lactobacillus속의 균주들은 모두 초기 pH 4.8 및 4.2에서 증식하였으나 4.0에서는 증식하지 못하였다. Glucose broth에서의 최종 pH는 Leu. mesenteroides의 균주들은 $3.85{\sim}4.10$이었고, lactobacillus속 균주들은 $3.82{\sim}3.99$이었다. 60균주 모두 litmus milk에서 우유를 응고시키지 못하였고, litmus를 환원시키지도 못하였다. Leu. mesenteroides와 Lactobacillus속의 균주들은 모두 에탄올 7% 함유배지와 NaCl 6.5% 함유배지에서 증식하였고, 에탄올 15% 함유배지와 NaCl 10% 함유배지에서는 증식하지 못하였다. 모든 균주들이 pH 3.5인 인공위액과 40%의 담즙액에서 내성을 나타내었다. 특히 Leu. mesenteroides의 균주들은 모두 pH 3.0인 인공위액에서도 내성을 나타내었다. 본 젖산균들의 생리적인 특성은 여러 점에서 Bergey's Manual of Systematic Bacteriology에 기재된 내용들과 일치하지 않으므로 더욱 정밀한 조사를 실시하여 분류학상의 위치를 정확히 밝혀 볼 필요가 있을 것으로 생각되었다.

• 한국식품영양학회지
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• 제9권3호
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• pp.341-347
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• 1996

Growth curves of seven strains of lactic acid bacteria isolated from Kimchi were graphed, when they were cultivated at 3$0^{\circ}C$ in filter sterilized Chinese cabbage juice containing 0, 2, 4 and 6% salt, and then lag time and generation time were calculated. The shapes of growth curves were changed differently among strains, as salt concentrations were increased. The addition of 2~4% salt resulted in prolongation of lag time were most omspicuous in Leu. Paramesenteroides and Leu. Mesenteroides subsp. Dextranicum, and the next in Leu. Mesenteroides subsp. Mesenteroides,m Lac. Bavaricus and Lac. Gomohiochii, and the least in Lac. Plantarum and Lac. Brevis. And then the prolongations of generation time were most remarkable in Lac. bavaricus and Lac. Homohiochii, and the next in Leu. Mesenteroides subsp. Mesenteroides, Leu. Mesenteroides subsp. Dextranicum and Leu. Paramesenteroides, and the least in Lac. Plantarum and Lac. brevis. By increasing salt concentrations from 0 to 2%, the generation times of Leu. Cesenteroides subsp. Dextranicum and Leu. Mesenteriodes subsp. Mesenteroides were prolonged slightly, while those of Lac. Homohiochii and Lac. Brevis were not changed, and those of Lac. Plantarum, Lac. Bavaricus and Leu. Paramesenteroides were shortened slightly. As salt concentrations were increased from 2% to 4%, inversions in the order of generation time occurred among strains. As a whole, lower salt concentrations were more favorable for the growth of Leuconostoc strains, while higher salt concentrations were for Lactobacillus strains.

• Journal of Microbiology and Biotechnology
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• 제30권6호
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• pp.830-838
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• 2020

The histone-like nucleoid structuring protein (H-NS) is an abundant global regulator of environmentally controlled gene expression. Herein, we demonstrate that H-NS represses the expression of LeuO, the master regulator of the cyclic(Phe-Pro)-dependent signaling pathway, by directly binding to the upstream region of the gene. H-NS binds to a long stretched region (more than 160-bp long), which overlaps with binding sites for ToxR and LeuO. A high quantity of H-NS outcompetes ToxR for binding to the cis-acting element of leuO. However, our footprinting analyses suggests that the binding of H-NS is relatively weaker than LeuO or ToxR at the same molarity. Considering that the DNA nucleotide sequences of the upstream regions of leuO genes are highly conserved among various Vibrio, such patterns as those found in V. vulnificus would be a common feature in the regulation of leuO gene expression in Vibrionaceae. Taken together, these results suggest that, in species belonging to Vibrionaceae, H-NS regulates the expression of leuO as a basal stopper when cFP-ToxR mediated signaling is absent.

• 한국식품저장유통학회지
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• 제15권5호
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• pp.760-768
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• 2008

EPS 생성 유산균인 Leu. kimchii GJ2의 생리활성 효능을 구명하기 위하여 고콜레스테롤식이를 급여한 흰쥐에게 Leu. kimchii GJ2 투여로 고지혈증 개선효과를 조사하였다. 체중증가율, 식이섭취량 및 식이효율은 실험군 간의 차이가 없었으나, 체중당 간의 무게는 고콜레스테롤식이군 (HCD)이 다른 실험군들에 비하여 유의하게 증가되었다. 고콜레스테롤식이 급여로 증가된 혈청 중 GOT 및 ALP 활성은 Leu. kimchii GJ2 투여 병합투여로 활성이 감소되었으며, Leu. kimchii GJ2 투여 용량이 증가할수록 농도 의존적으로 감소하였다. 혈청 중 중성지방과 인지질 함량은 실험군 간에 유의차가 없었으나, 총콜레스테롤 함량은 고콜레스테롤식이군(HCD군, HCD-LKL군 및 HCD-LKH군)들 간에 유의차를 보여 Leu. kimchii GJ2 투여 용량이 증가할수록 감소하였다. 고콜레스테롤식이와 Leu. kimchii GJ2 병합투여한 HCD-LKL군과 HCD-LKH군은 HCD군에 비하여 HDL-콜레스테롤 함량은 증가하였으나, LDL-콜레스테롤 함량, 심혈관위험지수 및 동맥경화지수는 유의하게 저하되었다. Leu. kimchii GJ2 투여 용량이 증가할수록 HDL-콜레스테롤 함량은 농도 의존적으로 증가하였고, LDL-콜레스테롤 함량은 저하되었다. 간조직 중 총콜레스테롤 및 중성 지방 함량은 HCD군이 ND군에 비하여 유의하게 증가되었으며, 고콜레스테롤식이와 Leu. kimchii GJ2 병합투여한 HCD-LKL군과 HCD-LKH군은 HCD군에 비하여 Leu. kimchii GJ2 투여 용량 의존적으로 저하되었다. 지방조직의 HR-LPL과 TE-LPL 활성은 HCD군이 다른 군들에 비하여 증가하였으며, Leu. kimchii GJ2 투여 용량이 증가할수록 HR-LPL과 TE-LPL 활성 모두 유의하게 저하되었다. 이상의 결과 Leu. kimchii GJ2은 고콜레스테롤식이 급여로 증가 되어진 총콜레스테롤 및 LDL-콜레스테롤 함량을 감소시키고, 감소되어진 HDL-콜레스테롤 함량을 증가시킴으로써 혈청 지질을 저하시키며, 간기능 보호효과가 있는 것으로 확인되어 고지혈증 예방과 치료에 효과가 있을 것으로 사료된다. Leu. kimchii GJ2의 이러한 효과는 Leu. kimchii GJ2가 EPS를 생성하여 유산균 본래의 기능인 장 운동 개선효과와 식이섬유소처럼 작용하여 지질의 장내에서의 흡수를 저해했기 때문이라 사료된다.

• Fisheries and Aquatic Sciences
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• 제8권2호
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• pp.109-112
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• 2005

A peptide that inhibits angiotensin-converting enzyme (ACE) was isolated from a hydrolysate of Manila clam (Ruditapes philippinarum) proteins prepared with thermolysin. Amino acid sequence of the peptide was determined to be Leu-Leu-Pro. Chemically synthesized Leu-Leu-Pro had an $IC_{50}\;value\;of\;158\;\mu{M}$. Peptides related to the Manila clam-derived peptide were synthesized to study the structure-activity relationships. The tetrapeptide, Leu-Leu-Pro-Pro, had a very weak effect on the enzyme. However, Leu-Leu-Pro-Asn showed no inhibitory activity.

• 한국식품영양과학회지
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• 제36권5호
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• pp.534-539
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• 2007

본 연구는 김치로 분리한 우량 종균인 Leu. citreum GJ7의 급성독성을 시험하기 위하여 ICR 마우스에게 1회 Leu. citreum GJ7을 복강 또는 경구투여한 후 사망률, 체중의 변화, 일반 및 임상증상, 육안적 소견 등을 관찰하였다. 복강투여 후 24시간 관찰한 결과, 일부 Leu. citreum GJ7 투여군에서 부분적으로 사망례가 관찰은 되었으나 나머지 시험동물은 계속 생존하여 2,500 mg/kg까지는 평균치사량을 산출할 수 없었다. 또한 5,000 mg/kg을 14일 동안 경구투여하였을 경우에는 사망례가 없었으며, 특이한 임상증상도 관찰되지 않았다. 복강 혹은 경구투여한 후 마우스의 체중변화에 있어서도 대조군과 Leu. citreum GJ7 투여군 사이에 유의성 있는 차이는 보이지 않았으며, 생존동물의 부검결과에서도 내부 장기의 육안적 이상이 관찰되지 않았다. 따라서 Leu. citreum GJ7은 본 실험의 모든 조건에서 $LD_{50}$이 복강투여 시 2,500 mg/kg, 경구투여 시 5,000 mg/kg 이상인 저독성의 안전한 물질로 사료된다.

• 약학회지
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• 제38권5호
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• pp.530-543
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• 1994

To study the feasibility of transmucosal delivery of leucine enkephalin (Leu-Enk) and $[D-ala^2]$-leucine enkephalinamide (YAGFL), their degradation extents and pathways in various rabbit mucosa extracts were investigated by high performance liquid chromatography. The degradation of Leu-Enk and YAGFL was observed to follow the first-order kinetics. The degradation half-lives of Leu-Enk in the nasal, rectal and vaginal mucosal extracts were 1.62, 0.37 and 1.12 hrs and those of YAGFL were 30.55, 9.70 and 6.82 hrs, respectively, indicating Leu-Enk was degraded in a more extensive and rapid manner than YAGFL. But the mucosal and serosal extracts of the same mucosa showed the similar degradation rates for both pentapeptides. The degradation was most rapid in the neutral pH and increasing concentrations of substrates retarded the degradation rates. The maior hydrolytic fragments of Leu-Enk were Des-Tyr-Leu-Enk and tyrosine, indicating the enzymatic hydrolysis by aminopeptidases. However, the data also suggested endopeptidases such as dipeptidyl carboxypeptidase and dipeptidyl aminopeptidase could play some role in the degradation of Leu-Enk. On the other hand, the hydrolytic fragments of YAGFL in all the mucosa extracts were mainly Tyr-D-Ala-Gly and Phe-Leu-Amide, demonstrating the hydrolytic breakdown by endopeptidases. The degradation pathways were further explored by concomitantly determining the formation of smaller metabolites of primary hydrolytic fragments of Leu-Enk and YAGFL in the mucosa extracts.

• BMB Reports
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• 제29권2호
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• pp.99-104
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• 1996

Site-directed substitutions were made to change the Ile91 of restriction endonuclease EcoRV to either Val, Ala or Gly to identify the role of Ile91 in recognition and catalysis, since substitution of Ile91 with Leu afforded dramatic effects on the activity and properties of restriction endonuclease EcoRV. These changes alter the size of the hydrophobic side chain at position 91 and thus might have revealed the reason for the altered phenotype of Ile91Leu. However, the properties of Ile91Val and Ile91Ala mutants were much like wild type EcoRV, in both activity and metal ion preference. Ile91Gly had very little activity with either $Mg^{2+}$ or $Mn^{2+}$ as cofactors. To try to understand the unusual $Mn^{2+}$ profile of the Ile91Leu mutant, two double mutants, Ile91Leu;Asp90Asn and Ile91Leu;Glu45Met were created. Both double mutants were seriously disabled by the second amino acid change. Ile91Leu;Glu45Met had some residual activity in the $Mn^{2+}$ reaction buffer, whereas the Ile91Leu;Asp90Asn displayed no detectable activity.

• Applied Biological Chemistry
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• 제34권4호
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• pp.334-338
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• 1991

고상법으로 새로운 반응기구에 의한 bradykinin 및 $(D-Phe7\;-Leu^8)$ bradykinin을 합성하였다. Coupling은 N, N'-dicyclohexylcarbodiimide로 행하였으며 HBr 용액으로 cleavage한 후 조펩티드는 high pressure liquid chromatography로 정제하였다. 이들 펩티드의 순도는 paper chromatography, thin layer chromatography, paper electrophoresis, 융점측정기 및 아미노산기분석기에 의하여 분석하였다. Endopeptidase인 ${\alpha}-chymotrypsin$과 trysin, exopeptidase인 carboxypeptidase A와 leucine aminopeptidase를 사용하여 in vitro 상에서 이들 펩티드의 분해실험을 하였다. ${\alpha}-Chymotrypsine$ 및 carboxypeptidase A에 의하여 이들 펩티드는 빠르게 분해하였으나 leucine aminopeptidase는 N-말단의 2번 위치에 proline의 imino결합 때문에 분해하지 않았다.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제2권2호
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• pp.164-168
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• 1999

Background: Wilson disease (WD) is an autosomal recessive disorder of copper transport and characterized by degenerative changes in the brain, liver dysfunction, and Kayser-Fleischer rings due to toxic accumulation of copper. Since the identification of Wilson disease gene (ATP7B), more than 80 mutations have been detected among the different ethnic groups. Methods: Twenty three children with Wilson disease were included in this study. They were all diagnosed by low serum ceruloplasmin and increased 24 hour urinary copper excretion with characteristic clinical findings. We analysed WD gene mutation by assessing the nucleotide sequence of exon 7, 8, 9 and 10 including intron-exon boundaries of ATP7B gene from genomic DNA. Results: Arg778Leu mutation was identified in 16 WD patients; three were homozygous and 13 were heterozygous for this mutation. Of the 46 alleles, 19 alleles had a Arg778Leu mutation (19/46=41%). Homozygote patients had neurologic forms of WD. Arg778Leu mutation was not found among 50 normal healthy persons. Conclusion: Arg778Leu mutation is a common mutation in Korean WD gene. Arg778Leu mutation screening might be used as a useful supplementary diagnostic test in some patients to confirm Wilson disease in Korea.