• BMB Reports
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• 제28권4호
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• pp.363-367
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• 1995

E. coli methionyl-tRNA synthetase is one of the class I tRNA synthetases. The Tryptophane residue at the position 461 located in the C-terminal domain of the enzyme is a key amino acid for the interaction with the anticodon of $tRNA^{Met}$. W461 was replaced with other amino acids to determine the chemical requirement for the interaction with the anticodon of $tRNA^{Met}$. Saturation mutagenesis at the position 461 generated a total of 12 substitution mutants of methionyl-tRNA synthetase. All the mutants showed the same in vivo stability as the wild-type enzyme, suggesting that the amino acid substitutions did not cause severe conformational change of the protein The mutants containing tyrosine, phenylalanine, histidine and cysteine substitutions showed in vivo activity while all the other mutants did not. The comparison of the in vitro aminoacylation activities of these mutants showed that aromatic ring structure, Van der Waals volume and hydrogen bond potential of the amino acid residue at the position 461 are the major determinants for the interaction with the anticodon of $tRNA^{Met}$.

• The Korean Journal of Physiology and Pharmacology
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• 제1권2호
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• pp.185-193
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• 1997

The characteristics of $Na^+$-dependent cycloleucine uptake was investigated in OK cells with regard to substrate specificity and regulation by protein kinase C (PKC). Inhibition studies with different synthetic and natural amino acids showed a broad spectrum affinity to neutral amino acids regardless of their different side chains including branched or aromatic, indicating that the $Na^+$-dependent cycloleucine uptake in OK cells is mediated by System $B^o$ or System $B^o$-like transporter rather than the classical System A or ASC. Phorbol 12-myristate 13-acetate (PMA) and phorbol 12,13-dibutyrate, but not $4{\alpha}-PMA$ elicited a time-dependent biphasic stimulation of $Na^+$-dependent cycloleucine uptake, which produced early transient peak at 30 min and late sustained peak at 180min. Both the early and late stimulations by PMA were due to an increase in Vmax and not due to a change in Km. PKC inhibitors blocked both the early and late stimulation by PMA, while protein synthesis inhibitors blocked the late stimulation only. These results suggest the existence and regulation by PKC of System $B^o$ or System $B^o$-like broad spectrum transport system for neutral amino acids in OK cells.

• 생명과학회지
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• 제17권2호통권82호
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• pp.286-292
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• 2007

마늘주의 산업화에 앞서 기초 자료로써 활용하고자, 마늘을 소주 등의 술에 침지하였을 때 마늘의 휘발성 기능성분과 유리아미노산이 술로 침출되는 정도 및 형태에 관하여 조사하고자, 생마늘을 20% 주정에 5주간 침지하고 매주 휘발성 향기성분과 유리아미노산들이 침출되는 양적 및 형태적 변화를 조사하였다. 마늘의 주요 유리 아미노산은 L-aspartic acid, L-glutamic acid, L-arginine, L-alanine, L- proline, L-asparagine 및 L-serine이었으며, 유리 아미노산들 모두 침지 기간의경과에 따라 침출량이 증가하였다. 또한, L-threonine, L-proline, L-valine 및 L-leucine 등의 중성아미노산들과 방향족아미노산인 tyrosine과 phenylalanine은 3주 후부터 80% 이상 침출된 반면에, 산성, 염기성 및 함황아미노산들은 5주 후에도 80% 미만이었다. 생마늘의 휘발성 향기성분은 diallyl trisulfide, diallyl disulfide, methyl allyl disulfide, 2-vinyl-4H-1,3-dithiin, 3-vinyl-3,4-dihydro-1,2-dithiin, 3,5-diethyl-1,24-trithiolane, isobutyl isothiocyanate 및 diallyl sulfide 등의 황화합물들이 주요 성분들이었다. 생마늘로부터 주정으로 침출된 휘발성 향기성분은 allyl alcohol, diallyl disulfide, 3,5-diethyl-1,2,4-trithiolane, diallyl trisulfide, 3,4-dimethoxyfuran의 5종이었으며, 침지기간의 경과에 따라 3,5-diethyl-1,2,4-trithiolane는 계속 침출량이 증가하였지만 그 외 4종은 감소하였다. 침 지기간 중 furfural, 5-methylfurfural, 5-hydroxymethylfurfural, dimethyl pyrazine, furfuryl alcohol, 3-hydroxy-2-bytanone과 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one이 새로이 생성되었으며, 침지기간의 경과에 따라 침출주에 대부분 축적되는 양상을 보였다.

• Journal of Microbiology
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• 제45권2호
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• pp.153-157
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• 2007

5-enolpyruvylshikimate-3-phosphate synthase (EPSP synthase, EC 2.5.1.19) is the sixth enzyme in the shikimate pathway which is essential for the synthesis of aromatic amino acids and many secondary metabolites. The enzyme is widely involved in glyphosate tolerant transgenic plants because it is the primary target of the nonselective herbicide glyphosate. In this study, the Dunaliella salina EPSP synthase gene was cloned by RT-PCR approach. It contains an open reading frame encoding a protein of 514 amino acids with a calculated molecular weight of 54.6 KDa. The derived amino acid sequence showed high homology with other EPSP synthases. The Dunaliella salina EPSP synthase gene was expressed in Escherichia coli and the recombinant EPSP synthase were identified by functional complementation assay.

• Mycobiology
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• 제43권3호
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• pp.327-332
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• 2015

Phenylalanine ammonia-lyase (PAL) gene is known to be expressed in plants, and is involved in the differentiation, growth and synthesis of secondary metabolites. However, its expression in fungi remains to be explored. To understand its expression in mushroom fungi, the PAL gene of the edible mushroom Flammulina velutipes (Fvpal) was cloned and characterized. The cloned Fvpal consists of 2,175 bp, coding for a polypeptide containing 724 amino acids and having 11 introns. The translated amino acid sequence of Fvpal shares a high identity (66%) with that of ectomycorrhizal fungus Tricholoma matsutake. Distinctively, the Fvpal expression in the mycelium was higher in minimal medium supplemented with L-tyrosine than with other aromatic amino acids. During cultivation of the mushroom on sawdust medium, Fvpal expression in the fruit body correspondingly increased as the mushroom grew. In the fruiting body, Fvpal was expressed more in the stipe than in the pileus. These results suggest that F. velutipes PAL activity differs in the different organs of the mushroom. Overall, this is first report to show that the PAL gene expression is associated with mushroom growth in fungi.

• KSBB Journal
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• 제24권1호
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• pp.75-79
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• 2009

Coenzyme $Q_{10}$ 고역가 변이주인 Agrobacterium tumefaciens KPU-11-03의 다양한 유기 질소원에 대한 coenzyme $Q_{10}$ 생산량과 coenzyme $Q_{10}$의 구성비율 등을 비교한 결과, CSP 첨가 시 coenzyme $Q_{10}$ 생산량은 212.7 mg/l, 구성비율은 94%로 다른 유기질소원에 비해 매우 높게 나타났다. 특히 Bacto tryptone, Bacto peptone, soybean meal, casamino acid 등의 유기 질소원 첨가 시에는 극히 낮은 coenzyme $Q_{10}$ 역가를 나타내어 균체내의 coenzyme $Q_{10}$의 축적은 유기 질소원의 종류 즉 아미노산의 종류 및 량과 상관성이 있음을 추정할 수 있었다. 또한 무기질소원에 대하여 실험한 결과, $(NH_4)_2SO_4$ 첨가 시에 coenzyme $Q_{10}$역가가 약 2배 증가하였고 다른 무기질소원에 사용 시에는 오히려 감소하였다. Coenzyme $Q_{10}$ 역가와 관련된 아미노산을 확인하기 위해 유기질소원으로 Bacto tryptone을 첨가한 배지에 9가지의 아미노산을 첨가하여 실혐한 결과, 방향족 아미노산인 tyrosine 첨가 시의 coenzyme $Q_{10}$ 생산량은 99.5 mg/l로 비첨가구보다 약 8.2배 증가하였으나 phenylalanine과 tryptophan등의 다른 방향족 아미노산의 첨가 시에는 coenzyme $Q_{10}$ 생산량이 오히려 감소하는 것으로 나타나 tyrosine의 첨가가 coenzyme $Q_{10}$ 역가에 매우 중요함을 확인하였다.

• Journal of Microbiology
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• 제44권1호
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• pp.50-53
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• 2006

Cys-29 and Cys-251 of Streptomyces albus valine dehydrogenase(ValDH) were highly conserved in the corresponding region of $NAD(P)^+$-dependent amino acid dehydroganase sequences. To ascertain the functional role of these cysteine residues in S. albus ValDH, site-directed mutagenesis was performed to change each of the two residues to serine. Kinetic analyses of the enzymes mutated at Cys-29 and Cys-251 revealed that these residues are involved in catalysis. We also constructed mutant ValDH by substituting valine for leucine at 305 by site-directed mutagenesis. This residue was chosen, because it has been proposed to be important for substrate discrimination by phenylalanine dehydrogenase (PheDH) and leucine dehydrogenase (LeuDH). Kinetic analysis of the V305L mutant enzyme revealed that it is involved in the substrate binding site. However it displayed less activity than the wild type enzyme toward all aliphatic and aromatic amino acids tested.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.219.4-220
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• 2002

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2001년도 제34회 학술심포지움
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• pp.21-28
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• 2001

A newly isolated Aspergillus niger possessing the novel epoxide hydrolase(EHase) activity was investigated for the enantioselective hydrolysis of racemic aromatic epoxides. The gene encoding EHase was cloned by RT-PCR, and molecular characteristics of the EHase gene were compared with other microbial EHases. The cloned gene encodes 398 amino acids with a deduced molecular mass of 44.5 kDa and pI of 4.83, and sequence homology with other microbial EHase was low. Functional recombinant EHase could be obtained by heterologous expressions in E. coli. Enantioselectivity of recombinant EHase was tested for valuable aromatic epoxide intermediates. Reaction conditions of EHase-catalyzed asymmetric resolution were optimized for the production of chiral styrene oxide.

• 미생물학회지
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• 제55권2호
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• pp.164-166
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• 2019

이 연구에서는 Microbacterium aurum KACC $15219^T$ (=IFO $15204^T$ = DSM $8600^T$)의 완전한 유전체 서열이 해독되었다. 하나의 원형 염색체는 3.42 Mbp였으며 G+C 함량이 69.9%였다. 해당 염색체 염기서열을 주석화한 결과, 총 3,096개의 유전자 서열이 발견되었다. 16종 이상의 탄소원을 분해하는 것으로 알려진 M. aurum KACC $15219^T$에는 방향족 아미노산 합성 기질인 quinic acid를 비롯한 다양한 탄소원의 이용과 관련된 유전자가 존재하였다. M. aurum KACC $15219^T$의 유전체 정보는 이 미생물에 대한 이해를 높이고 산업적인 이용을 위한 기반이 될 것이다.