• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.1144-1148
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• 2006

DNA can oxidatively be deaminated by ROS, which converts DNA base amino groups to keto groups and can trigger abnormal mutations, resulting in mutagenesis in organisms. In this study, a noncanonical purine dNTP pyrophosphatase (AfPPase) from a hyperthermophilic archaeon Archaeoglobus fulgidus, which hydrolyzes aberrant nucleoside triphosphates, was overexpressed in E. coli, purified, and characterized. The purified AfPPase showed remarkably high activity for XTP and dITP, suggesting that the 6-keto group of these nucleotides is critical for the reactivity. Under optimal reaction conditions, the reaction rate for these substrates was about 120 times that with dGTP. Therefore, AfPPase may play a significant role in DNA repair by hydrolysis of noncanonical nucleotides before they are misincorporated into DNA.

• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.610-613
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• 1991

Some of the Kinetic properties of crystallic xanthine dehydrogenase form Pseudomonas synxantha A3 were studied. The enzyme activity was strongly inhibited by adenine, 8-azaadenine, 2-methyladenine, guanine, and 8-azaguanine, but not by caffeine, and the inhibitions by adenine and guanine were observed to be of noncompetitive type. The $K_i$ values for adenine and guanine were 0.037 and 0.098 mM, respectively. Michaelis constants were found to be 0.33 and 0.06 rnM for hypoxanthine and xanthine with $NAD^+$ as the second substrate, respectively, and 0.1 rnM for $NAD^+$ with either hypoxanthine or xanthine as the second substrate.

• Journal of Microbiology and Biotechnology
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• v.30 no.1
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• pp.11-20
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• 2020

Quercetin and its derivatives are important metabolites that belong to the flavonol class of flavonoids. Quercetin and some of the conjugates have been approved by the FDA for human use. They are widely distributed among plants and have various biological activities, such as being anticancer, antiviral, and antioxidant. Hence, the biosynthesis of novel derivatives is an important field of research. Glycosylation and methylation are two important modification strategies that have long been used and have resulted in many novel metabolites that are not present in natural sources. A strategy for modifying quercetin in E. coli by means of glycosylation, for example, involves overexpressing respective glycosyltransferases (GTs) in the host and metabolic engineering for increasing nucleoside diphosphate sugar (NDP-sugar). Still others have used microorganisms other than E. coli, such as Streptomyces sp., for the biotransformation process. The overall study of the structural activity relationship has revealed that modification of some residues in quercetin decreased one activity but increased others. This review summarizes all of the information mentioned above.

• The Korean Journal of Malacology
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• v.14 no.2
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• pp.103-111
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• 1998

참굴에 다환성방향족탄화수소(PAHs)의 축적성과 이 물질들이 미치는 독성을 평가하기 위해 해양환경에서 빈번히 검출되는 PAHs 중의 하나인 fluoranthene을 사용한 모델연구를 수행하였다. Fluoranthene을 0.01-1ppm의 농도로 2주간 참굴에 노출시켰을 때 참굴 조직내의 fluoranthene의 농도는 노출기간 및 노출농도에 비례하여 최고 40-70배까지 증가하였다. 소화맹낭과 폐각근의 지질 과산화물가는 노출기간 및 노출농도에 관련하여 현저히 증가하였으며 수용성단백질의 함량은 노출기간이 길어짐에 따라 서서히 감소하였다. 그러나 glycogen 함량, nucleoside/nucleotide, DNA 및 RNA 함량은 변화하지 않았다. 이 결과로 fluoranthene은 굴의 조직내로 원활하게 축적함을 확인하였다. 또한 과산화지질의 함량은 fluoranthene에의 오염에 대해 신속히 반응하는 지표의 하나로 추정되며 수용성단백질의 감소도 비록 시간적으로 다소 둔감하기는 하나 또 다른 지표가 될 수 있을 것으로 사료된다.

• The Korean Journal of Malacology
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• v.14 no.2
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• pp.113-120
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• 1998

참굴에 다환성방향족탄화수소(PAHs)의 축적성과 이 물질들이 미치는 독성을 평가하기 위해 해양환경에서 빈번히 검출되는 PAHs 중의 하나인 anthracene을 사용한 모델연구를 수행하였다. Anthracene을 0.01-1ppm의 농도로 2주간 참굴에 노출시켰을 때 참굴 조직내의 anthracene의 농도는 노출기간 및 노출강도에 비례하여 최고 25-85배까지 증가하였다. 소화맹낭과 폐각근의 지질 과산화물가는 노출기간 및 노출농도에 관련하여 현저히 증가하였으나 수용성단백질, glycogen, nucleoside/nucleotide 및 핵산의 함량은 변화하지 않았다. 이 결과로 anthracene은 굴의 조직내로 원할하게 축적됨을 확인하였으며 과산화지질의 함량은 anthracene에의 오염에 대한 예민한 생화학적 지표가 될 수 있을 것으로 사료된다.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3621-3628
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• 2013

Novel 5'-deoxythreosyl purine phosphonic acid analogues containing a 2'-electropositive moiety such as fluorine atom, were designed and synthesized from commercially available 1,3-dihydroxy acetone. Condensation successfully proceeded from a glycosyl donor 6 under Vorbr$\ddot{u}$ggen conditions and cross-metathesis gave the desired phosphonate analogues 7a, 7b, 17a and 17b. The synthesized nucleoside phosphonic acid analogues 13, 16, 23, 26, 28 were subjected to antiviral screening against HIV-1. The bis(SATE) adenine analogue 28 exhibited significant in vitro activities against HIV-1.

• Bulletin of the Korean Chemical Society
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• v.31 no.8
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• pp.2180-2184
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• 2010

We synthesized and tested the anti-HIV activity of the SATE prodrug of a 2'-methyl 5'-norcarbocyclic adenine analogue. The introduction of a methyl group in the 2'-position was performed by the addition of a carbonyl using isopropenyl magnesium bromide. The adenine base was efficiently coupled using the Mitsunobu reaction. The chemical stability study of the bis(SATE) derivative 18 was measured at neutral (pH 7.2) and slightly acid (milli-Q water, pH 5.5) pH, and compounds 16 and 18 were evaluated as potential anti-HIV-1 agents.

• YAKHAK HOEJI
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• v.54 no.6
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• pp.474-480
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• 2010

Conformationally locked nucleosides are important in searching selective agonists and antagonists for P2Y receptors. There were two previous synthetic works of the crucial intermediate, cyclopentenyl alcohol (3), which had some inefficiency like using too strong dianionic base and synthesis of racemate. Here we describes a facile synthesis of the intermediate using Sharpless epoxidation and the opening of epoxide ring using zinc, followed by Grubb's metathesis as key steps. The intermediate was converted to the southern bicyclo[3.2.0]heptane for confirming its usefulness.

• CELLMED
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• v.2 no.2
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• pp.14.1-14.7
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• 2012

Cordycepin, a nucleoside derivative, was extracted from $Cordyceps$ $sinensis$, and then proved to be a bioactive compound present in traditional Chinese medicine Cordyceps. Early investigations revealed cordycepin possessed anti-microbial activity mainly by inhibiting nucleic acid synthesis. Although cordycepin is not used as antibacterial agents in clinic, its other pharmacological effects and possible mechanisms have gradually been deeply studied. This review serves to summarize the research progress of cordycepin.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.34-35
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• 2005