• Journal of Microbiology and Biotechnology
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• 제22권10호
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• pp.1311-1323
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• 2012

In the present work, current knowledge on the potential fate, microbial degradation, and toxicity of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) was thoroughly reviewed, focusing on the toxicological assessment of a variety of potential RDX degradation pathways in bacteria and fungi. The present review on microbial degradation pathways and toxicities of degradation intermediates suggests that, among aerobic RDX degradation pathways, the one via denitration may be preferred in a toxicological perspective, and that among anaerobic pathways, those forming 4-nitro-2,4-diazabutanal (NDAB) via ring cleavage of 1-nitroso-3,5-dinitro-1,3,5-triazinane (MNX) may be toxicologically advantageous owing to its potential mineralization under partial or complete anoxic conditions. These findings provide important information on RDX-degrading microbial pathways, toxicologically most suitable to be stimulated in contaminated fields.

• Bulletin of the Korean Chemical Society
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• 제18권4호
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• pp.390-394
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• 1997

Nucleophilic substitution reactions of 2-thiopheneethyl benzenesulfonates (2-TEB) and 3-thiopheneethyl benzenesulfonates (3-TEB) with anilines and N,N-dimethylanilines (DMA) are investigated in acetonitrile at 60.0 ℃. The cross-interaction constants ρxz determined for the reactions with anilines are large negative (- 0.50) which are comparable to those for the similar predominantly frontside-attack SN2 reactions of 1-phenylethyl (1-PEB), 2-phenylethyl (2-PEB) and cumyl benzenesulfonates. A large negative ρxz value (- 0.4∼- 0.8) is considered to provide a mechanistic criterion for the frontside-attack SN2 mechanism with a four-center transition state. In agreement with this proposal the kinetic isotope effects, kH/kD, involving deuterated aniline nucleophiles are all greater than one reflecting partial N-H(D) bond cleavage in the transition state. The MO theoretical reactant structures of 1-PEB, 2-PEB and 2-TEB based on the PM3 calculation show that the benzene ring blocks the backside nucleophile approach to the reaction center carbon (Cα) enforcing the frontside-attack SN2 mechanism.

• Journal of Microbiology and Biotechnology
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• 제5권2호
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• pp.68-73
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• 1995

Pseudomonas sp. P20 was shown to be capable of degrading biphenyl and 4-chlorobiphenyl (4CB) to produce the corresponding benzoic acids wnich were not further degraded. But the potential of the strain for biodegradation of 4CB was shown to be excellent. The pcbA, B, C and D genes responsible for the aromatic ring-cleavage of biphenyl and 4CB degradation were cloned from the chromosomal DNA of the strain. In this study, the pebC and D genes specifying degradation of 2, 3-dihydroxybiphenyl (2, 3-DHBP) produced from biphenyl by the pebAB-encoded enzymes were cloned by using pBluescript SK(＋) as a vector. From the pCK102 (9.3 kb) containing pebC and D genes, pCK1022 inserted with a EcoRI-HindIII DNA fragment (4.1 kb) carrying pebC and D and a pCK1092 inserted with EcoRI-XbaI fragment (1.95 kb) carrying pebC were constructed. The expression of pcbC and D' in E. coli CK102 and pebC in E. coli CK1092 was examined by gas chromatography and UV-vis spectrophotometry. 2.3-dihydroxybiphenyl was readily degraded to produce meta-cleavage product (MCP) by E. coli CK102 after incubation for 10 min, and then only benzoic acid(BA) was detected in the 24-h old culture. The MCP was detected in E. coli CK1022 containing pebC and 0 genes (by the resting cells assay) for up to 3 h after incubation and then diminished completely in 8 h, whereas the MCP accumulated in the E. coli CK1092 culture even after 6 h of incubation. The 2, 3-DHBP dioxygenases (product of pebC gene) produced by E. coli CK1, CK102, CK1023, and CK1092 strains were measured by native PAGE analysis to be about 250 kDa in molecular weight, which were about same as those of Pseudomonas sp. DJ-12, P. pseudoa1caligenes KF707, and P. putida OU83.

• 유기물자원화
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• 제11권4호
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• pp.130-137
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• 2003

본 연구에서는 페놀에 적응된 미생물을 순수 분리하여 다고리 방향족 탄화수소(PAH)분해에 이용 하고자 하였으며, PAH분해하는 과정에서 나타나는 특성을 파악하고자 하였다. 분리된 미생물은 Stenotrophomonas maltophilia로 동정되었으며, 페놀의 분해경향은 낮은 농도에서 빠른 분해속도 상수값을 가지며, 미생물의 성장률은 0.1447mg cell/mg phenol로 나타났다. 나프탈렌과 페놀의 공존 시 페놀의 분해를 선호하고, 나프탈렌 및 페난스렌을 성장기질로 이용하는 특성을 가지고 있으나, 파이렌과 같이 4개 이상의 고리구조를 가진 PAH의 분해는 이루어지지 않았다. PAH 분해경로는 dioxygenation에 의한 두개의 hydroxy group이 C-1과 C-2에 첨가된 상태에서 ortho cleavage가 일어나고 순차적으로 Decarboxylation이 일어나는 것으로 판단되었다.

• 대한화학회지
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• 제22권6호
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• pp.396-402
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• 1978

N-아세틸피페리돈과 그 양성자 첨가물의 형태 및 산-촉매 친핵성 치환반응에 대하여 EHT 및 CNDO/2 MO법과 궤도함수 혼합법을 적용하여 연구하였다. 계산 결과는 분자의 형태가 half-chair, cis-trans형이 가장 안정하며 양성자화는 아세틸카르보닐 산소에서 더 용이하게 일어남을 나타내고 있다. 이 결과를 콘쥬게이션, 정전기적 및 입체효과로서 설명하였다. 그리고 전하-조절 반응에서는 카르보닐 탄소원자의 양전하의 증가가, 궤도함수 조절반응에서는 LUMO AO 계수의 증가가 양성자화된 카르보닐 탄소의 반응성을 크게 증가시켜 친핵성 치환반응에서는 아세틸 절단이 개환반응보다 용이함을 밝혔다.

• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.804-810
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• 1999

There is a possibility that carvone, a monoterpene from spearmint (Mentha spicata), could induce the bph degradative pathway and genes in Alcaligenes eutrophus H850, which is a known Gram-negative PCB degrader with a broad substrate specificity that was thoroughly investigated with Arthrobacter sp. BIB, a Gram-positive PCB degrader. The strains BIB and H850 were unable to utilize and grow on the plant terpene [(R)-(-)-carvone] (50ppm) to be recognized as a sole carbon source. Nevertheless, the carvone did induce 2,3-dihydroxybiphenyl 1,2-dioxygenase (encoded by bphC) in the strain B lB, as observed by a resting cell assay that monitors accumulation of a yellow meta ring fission product from 4,4'-dichlorobiphenyl (DCBp). The monoterpene, however, did not appear to induce the meta cleavage pathway in the strain H850. Instead, an assumption was made that the strain might be using an alternative pathway, probably the ortho-cleavage pathway. A reverse transcription (RT)-PCR system, utilizing primers designed from a conserved region of the bphC gene of Arthrobacter sp. M5, was employed to verify the occurrence of the alternative pathway. A successful amplification (182bp) of mRNA transcribed from the N-terminal region of the bphC gene was accomplished in H850 cells induced by carvone (50ppm) as well as in biphenyl-growth cells. It is, therefore, likely that H850 possesses a specific PCB degradation pathway and hence a different substrate specificity compared with B1B. This study will contribute to an elucidation of the dynamic aspects of PCB bioremediation in terms of roles played by PCB degraders and plant terpenes as natural inducer substrates that are ubiquitous and environmentally compatible.

• Bulletin of the Korean Chemical Society
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• 제18권11호
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• pp.1166-1172
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• 1997

[FeⅢ(BLPA)DBC]BPh4, a new functional model for the catechol dioxygenases, has been synthesized, where BLPA is bis((6-methyl-2-pyridyl)methyl)(2-pyridylmethyl)amine and DBC is 3,5-di-tert-butylcatecholate dianion. The BLPA complex has a structural feature that iron center has a six-coordinate geometry with N4O2 donor set. It exhibits EPR signals at g=5.5 and 8.0 which are typical values for the high-spin FeⅢ (S=5/2) complex with axial symmetry. The BLPA complex reacts with O2 within a few hours to afford intradiol cleavage (75%) and extradiol cleavage (15%) products which is very unique result of all [Fe(L)DBC] complexes studied. The iron-catecholate interaction of BLPA complex is significantly stronger, resulting in the enhanced covalency of the metal-catecholate bonds and low energy catecholate to FeⅢ charge transfer bands at 583 and 962 nm in CH3CN. The enhanced covalency is also reflected by the isotropic shifts exhibited by the DBC protons, which indicate increased semiquinone character. The greater semiquinone character in the BLPA complex correlates well with its high reactivity towards O2. Kinetic studies of the reaction of the BLPA complex with 1 atm O2 in CH3OH and CH2Cl2 under pseudo-first order conditions show that the BLPA complex reacts with O2 much slower than the TPA complex, where TPA is tris(2-pyridylmethyl)amine. It is presumably due to the steric effect of the methyl substituent on the pyridine ring. Nevertheless, both the high specificity and the fast kinetics can be rationalized on the basis of its low energy catecholate to FeⅢ charge transfer bands and large isotropic NMR shifts for the BLPA protons. These results provide insight into the nature of the oxygenation mechanism of the catechol dioxygenases.

• BMB Reports
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• 제40권4호
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• pp.571-576
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• 2007

Three anti-apoptosis genes, Ls-iap2, iap3 and p49 were found in Leucania separata multiple nuclear polyhedrovirus. Amino acid sequence homology of Ls-IAP2 and Ls-IAP3 with Op-IAP2 and Op-IAP3 from Orgyia pseddotsugata MNPV were 20% and 42%, while that of Ls-P49 is 28% with Sl-P49 from Spodoptera littorolis MNPV. Ls-IAP2 contains one baculoviral IAP repeat (BIR) domain followed by a RING domain, while Ls-IAP3 contains two BIRs and a RING. Ls-P49 contains a reactive site loop, predicted cleavage site (KKLD$^{74}{\downarrow}$G) that is different from Sl-P49 (TVID$^{94}{\downarrow}$G). Expressed Ls-iap3 or Ls-p49 under presence of actinomycin D in SF9 cells, DNA ladder assayrevealed that Ls- IAP3 or Ls-P49 could block the apoptosis of SF9 cells induced by actinomycin D. Replication of p35 deficient-mutant Autographa californica MNPV in SF9 cells was also rescued when Ls-iap3 or Ls-p49 was expressed transiently. No anti-apoptotic activity was observed for Ls-IAP2. The results showed that both of Ls-IAP3 and Ls-P49 were functional apoptotic suppressors in SF9 cells.

• 한국식품영양과학회지
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• 제3권1호
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• pp.69-76
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• 1974

The method of amino acid sequence determination from the C-terminal amino acid is proposed and mass spectrometric identification of thiohydantoins described previously. In this paper was discussed the fragmentation of thiohydantoin-ring by deutero substitution and model tripeptide have been degraded through three stages each, with interpretable results. The conditions employed in this method are mild enough for biological materials. The main features of the method are the following. 1. Thiohydantoins were formed in a non-aqueous medium a mixture of acetic anhydride, acetic acid and ammonium thiocyanate. 2. Mass sepectra of thiohydantoins derived from 20 amino acids were obtained with a mass spectrometer, JEOL model JMS-06H. 3. Cleavage of peptidyl thiohydantoin was made with an acidic from of a cation-exchange resin. (Amberlite IR-120) 4. Separation of the cleaved thiohydantoin and the parent peptide less one amino acid moiety was made by chromatography on a Sephadex G-10 column. 5. The peptide fraction was concentrated by freezedrying. 6. Thiohydantoin derivative of carboxyl terminal amino acid residue was introduced with a direct inlet probe in methanol solution.

• BMB Reports
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• 제32권4호
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• pp.399-404
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• 1999

2,3-Dihydroxybiphenyl 1,2-dioxygenase (2,3-DHBD), which catalyzes the ring meta-cleavage of 2,3-dihydroxybiphenyl, is encoded by the phnQ gene of biphenyl- and phenanthrene-degrading Pseudomonas sp. strain DJ77. We determined the nucleotide sequence of a DNA fragment of 1497 base pairs which included the phnQ gene. The fragment lncluded an open reading frame of 903 base pairs to accommodate the enzyme. The predicted amino acid sequence of the enzyme subunit consisted of 300 residues. In front of the gene, a sequence resembling an E. coli promoter was identified, which led to constitutive expression of the cloned gene in E. coli. The deduced amino acid sequence of the PhnQ enzyme exhibited 85.6% identity with that of the corresponding enzyme in Sphingomonas yanoikuyae Q1 (formerly S. paucimobilis Q1) and 22.1% identity with that of catechol 1,2,3-dioxygenase from the same DJ77 strain. PhnQ showed broader substrate preference than previously-cloned PhnE, catechol 2,3-dioxygenase. Ten amino acid residues, considered to be important for the role of extradiol dioxygenases, were conserved.