• Bulletin of the Korean Chemical Society
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• 제9권6호
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• pp.412-412
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• 1988

• 한국동물위생학회지
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• 제22권2호
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• pp.105-111
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• 1999

This survey was carried out to detect the residual antibiotics in muscles of slaughter cattle from slaughter houses in Seoul from 1991 to 1998 using by EEC-4-plate method. The results were summarized as follows ; 1. Residual materials were detected in 402 samples(3.12%) by EEC-4-plate method. The detection ratios were highest in 1995 (9.51%), autumn (39.8%), Kyeonggi province (54.2%), Holestain(60.4%) and male(50.7%). 2. Residual antibiotics for 18 samples were classified as TCs(72.2%), sulfonamides(38.8% ) and $\beta$-lactams(5.5%) by HPLC 3. The residual concentration of oxytetracycline, sulfonamide and $\beta$-lactams were 0.34~15.93ppm, 0.17~1.18ppm and 0.06ppm, respectively.

• Bulletin of the Korean Chemical Society
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• 제15권6호
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• pp.453-455
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• 1994

Semiempirical MO calculations are applied to estimate the substituent effects on acylations of the nonfused N-vinyl-2-amino $\beta-lactams$ having frameworks analogous to 3-cephems. The stabilization energy for the reaction intermediate of the nucleophilic attack by the hydroxide ion is selected as the reactivity index and calculated by AM1 and PM3 methods for the model $\beta-lactams$ with substituents at the C1 and N-vinyl terminal positions. The reactivities are larger for -SH connected to the C1 and strong $\pi-acceptors$ at the N-vinyl terminal implying the large reactivity for known active cephalosporins. Quantum chemical calculation of stabilization energy could be useful in correlating antibiotic activities of many compounds obtained as derivatives of a lead compound.

• Bulletin of the Korean Chemical Society
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• 제21권5호
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• pp.541-543
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• 2000

• Biomolecules & Therapeutics
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• 제31권2호
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• pp.141-147
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• 2023

Antibiotic resistance has emerged as a global threat to modern healthcare systems and has nullified many commonly used antibiotics. β-Lactam antibiotics are among the most successful and occupy approximately two-thirds of the prescription antibiotic market. They inhibit the synthesis of the peptidoglycan layer in the bacterial cell wall by mimicking the D-Ala-D-Ala in the pentapeptide crosslinking neighboring glycan chains. To date, various β-lactam antibiotics have been developed to increase the spectrum of activity and evade drug resistance. This review emphasizes the three-dimensional structural characteristics of β-lactam antibiotics regarding the overall scaffold, working mechanism, chemical diversity, and hydrolysis mechanism by β-lactamases. The structural insight into various β-lactams will provide an in-depth understanding of the antibacterial efficacy and susceptibility to drug resistance in multidrug-resistant bacteria and help to develop better β-lactam antibiotics and inhibitors.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2005년도 제45회 학술심포지움 및 추계학술대회
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• pp.66-66
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• 2005

• Bulletin of the Korean Chemical Society
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• 제28권7호
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• pp.1085-1086
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• 2007

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.2863-2864
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• 2009

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.314.1-314.1
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• 2002

Bacterial ${\beta}$-lactamases provide resistance to ${\beta}$-lactams by hydrolyzing the ${\beta}$-lactam bond, On the basis of their catalytic mechanisms. ${\beta}$-lactamases are divided into two major groups. Class A. C and D which belong to the first group require serine in the active site and class B which is the second group require Zn(II) for their activity. Among class B enzymes, Bacteroides fragilis ${\beta}$-lactamase (CcrA enzyme) require two Zn(II) ions per monomer for maximal enzymatic activities. (omitted)

• Journal of Microbiology and Biotechnology
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• 제20권3호
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• pp.501-505
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• 2010

1-Acetyl-$\beta$-carboline was isolated as an anti-MRSA agent from the fermentation broth of a marine actinomycete isolated from marine sediment. The producing strain was identified to be Streptomyces sp. by phylogenetic analysis of the 16S rRNA gene sequence. The anti-MRSA agent was isolated by bioactivity-guided fractionation of the culture extract by solvent partitioning, ODS open flash chromatography, and purification with a reversed-phase HPLC. Its structure was elucidated by extensive 2D NMR and mass spectral analyses. Combination of 1-acetyl-$\beta$-carboline with ampicillin exhibited synergistic antibacterial activity against MRSA.