• Title/Summary/Keyword: combinatorial screening

Search Result 39, Processing Time 0.027 seconds

Establishment of new cytotoxicity screening system using Caco-2 cells

  • Seok, Ji-Eun;Kim, Ki-Hwan;Kim, Dong-Chool
    • Proceedings of the PSK Conference
    • /
    • 2002.10a
    • /
    • pp.92-93
    • /
    • 2002
  • With the recent development of combinatorial chemistry, recombinant biotechnology and rational drug design, millions of compounds are being produced in the laboratories of pharmaceutical companies. These new drug candidates are evaluated their efficacy and toxicity through in vivo animal model studies which is very important in drug development. From these studies, very successful drug candidates are selected. (omitted)

  • PDF

신약개발 환경의 변화와 대응책

  • 유성은
    • Proceedings of the Korean Society of Applied Pharmacology
    • /
    • 2000.04a
    • /
    • pp.1-2
    • /
    • 2000
  • 일반적인 신약 개발 방법으로는 천연물로부터 선도화합물이 발견되었을 때 의약화학자들은 그 물질의 화학구조식 중에서 약리 작용에 필수 요건이 되는 구조 요소를 규정하고, 체계적인 분자변형을 통하여 약리 작용의 최적화 작업을 추진한다. 그러나 분자 내에 여러 가지 치환기를 도입할 수 있는 경우 수많은 유도체가 합성 가능하며, 실제로 이와 같은 많은 수의 유도체를 합성한다는 것은 현실적으로 불가능하다. 통계적으로 하나의 신약 개발에 드는 시간과 경비는 약 10년 이상의 기간과 3,000 억원 이상의 경비가 소요된다. 따라서 시간과 경비를 줄이는 노력의 하나로 실험분야에서는 조합 화학합성 (Combinatorial Chemical Synthesis, CCS) 기술인 새로운 개념의 고효율 합성 기술이나 이를 대량 검색할 수 있는 초고속 활성 검색법 (High Through-put Screening, HTS) 기술이 1990년대 초에 본격적으로 각광 받게되었고, 정보관리 시스템을 통한 library 구축, 컴퓨터를 이용한 구조-활성 관계 및 분자 설계 기법이 급속히 발전하게 되었다. 따라서 기존의 random screening에 의한 신약개발 방법으로부터 탈피하여 새로운 차원의 신의약 개발 방법의 필요성이 절실히 요구되고 있다.

  • PDF

Construction of a Large Synthetic Human Fab Antibody Library on Yeast Cell Surface by Optimized Yeast Mating

  • Baek, Du-San;Kim, Yong-Sung
    • Journal of Microbiology and Biotechnology
    • /
    • v.24 no.3
    • /
    • pp.408-420
    • /
    • 2014
  • Yeast surface-displayed antibody libraries provide an efficient and quantitative screening resource for given antigens, but suffer from typically modest library sizes owing to low yeast transformation efficiency. Yeast mating is an attractive method for overcoming the limit of yeast transformation to construct a large, combinatorial antibody library, but the optimal conditions have not been reported. Here, we report a large synthetic human Fab (antigen binding fragment) yeast surface-displayed library generated by stepwise optimization of yeast mating conditions. We first constructed HC (heavy chain) and LC (light chain) libraries, where all of the six CDRs (complementarity-determining regions) of the variable domains were diversified mimicking the human germline antibody repertoires by degenerate codons, onto single frameworks of VH3-23 and $V{\kappa}1$-16 germline sequences, in two haploid cells of opposite mating types. Yeast mating conditions were optimized in the order of cell density, media pH, and cell growth phase, yielding a mating efficiency of ~58% between the two haploid cells carrying HC and LC libraries. We constructed two combinatorial Fab libraries with CDR-H3 of 9 or 11 residues in length with colony diversities of more than $10^9$ by one round of yeast mating between the two haploid HC and LC libraries, with modest diversity sizes of ${\sim}10^7$. The synthetic human Fab yeast-displayed libraries exhibited relative amino acid compositions in each position of the six CDRs that were very similar to those of the designed repertoires, suggesting that they are a promising source for human Fab antibody screening.

Identification of Novel Bioactive Hexapeptides Against Phytopathogenic Bacteria Through Rapid Screening of a Synthetic Combinatorial Library

  • Choi, Jae-Hyuk;Moon, Eun-Pyo
    • Journal of Microbiology and Biotechnology
    • /
    • v.19 no.8
    • /
    • pp.792-802
    • /
    • 2009
  • Antimicrobial peptides (AMPs) are considered to be a promising alternative to conventional antibiotics for future generations. We identified four novel hexapeptides with antimicrobial activity: KCM11 (TWWRWW-$NH_2$), KCM12 (KWRWlW-$NH_2$), KCM21 (KWWWRW-$NH_2$), and KRS22 (WRWFIH-$NH_2$), through positional scanning of a synthetic peptide combinatorial library (PS-SCL). The ability of these peptides to inhibit the growth of a variety of bacteria and unicellular fungi was evaluated. KCM11 and KRS22 preferentially inhibited the normal growth of fungal strains, whereas KCM12 and KCM21 were more active against bacterial strains. Bactericidal activity was addressed in a clear zone assay against phytopathogenic bacteria, including Pectobacterium spp., Xanthomonas spp., Pseudomonas spp., etc. KCM21 showed the highest activity and was effective against a wide range of target organisms. Application of KCM21 with inoculation of Pectobacterium carotovorum subsp. carotovorum on detached cabbage leaves resulted in an immune phenotype or a significant reduction in symptom development, depending on the peptide concentration. Cytotoxicity of the four hexapeptides was evaluated in mouse and human epithelial cell lines using an MTT test. The results revealed a lack of cytotoxic effects.

A Search for Red Phosphors Using Genetic Algorithm and Combinatorial Chemistry (유전알고리즘과 조합화학을 이용한 형광체 개발)

  • 이재문;유정곤;박덕현;손기선
    • Journal of the Korean Ceramic Society
    • /
    • v.40 no.12
    • /
    • pp.1170-1176
    • /
    • 2003
  • We developed an evolutionary optimization process involving a genetic algorithm and combinatorial chemistry (combi-chem), which was tailored exclusively for tile development of LED phosphors with a high luminescent efficiency, when excited by soft ultra violet irradiation. The ultimate goal of our study was to develop oxide red phosphors, which are suitable for three-band white Light Emitting Diodes (LED). To accomplish this, a computational evolutionary optimization process was adopted to screen a Eu$^{3+}$-doped alkali earth borosilicate system. The genetic algorithm is a well-known, very efficient heuristic optimization method and combi-chem is also a powerful tool for use in an actual experimental optimization process. Therefore the combination of a genetic algorithm and combi-chem would enhance the searching efficiency when applied to phosphor screening. Vertical simulations and an actual synthesis were carried out and promising red phosphors for three-band white LED applications, such as Eu$_{0.14}$Mg$_{0.18}$Ca$_{0.07}$Ba$_{0.12}$B$_{0.17}$Si$_{0.32}$O$_{\delta}$, were obtained.

A Novel Screening Strategy for Salt-resistant Alpha-helical Antimicrobial Peptides from a Phage Display Library (Phage Display Library를 이용한 Salt-Resistant Alpha-Helical 항균 펩타이드의 새로운 탐색방법)

  • Park, Ju-Hee;Han, Ok-Kyung;Lee, Baek-Rak;Kim, Jeong-Hyun
    • Microbiology and Biotechnology Letters
    • /
    • v.35 no.4
    • /
    • pp.278-284
    • /
    • 2007
  • A novel screening strategy for salt-resistant antimicrobial peptides from a M13 peptide library was developed. Fusion of MSI-344, a magainin derivative and indolicidin to pIII coat proteins did not significantly affect viability of the recombinant phages, which indicated that the pIII could neutralize toxicity of the antimicrobial peptides and therefore it is possible to construct antimicrobial peptide library in Escherichia coli. On the basis of the conserved sequence of ${\alpha}$-helical antimicrobial peptides, a semi-combinatorial peptide library was constructed in which the peptides were displayed by pIII. To remove hemolytic activity from the library, the phages bound to red blood cells were removed, and the subtracted phage library was screened for binding to target bacteria Pseudomonas aeruginosa and Staphylococcus aureus under high salt concentrations. The screened peptides showed relatively low antimicrobial activity against the target bacteria. However, antimicrobial activities of the screened peptides P06 and S18 were not affected by the cation concentrations of 150 mM $Na^+$, 2 mM $Mg^{2+}$ and 2 mM $Ca^{2+}$ without significant hemolytic activity. This screening strategy that is based on binding capacity to target cells provides new potential to develop salt-tolerant antimicrobial peptides.

Future of Toxicology and Role of Asian Chemical Safety Network

  • Kaminuma, Tsuguchika
    • Toxicological Research
    • /
    • v.17
    • /
    • pp.241-249
    • /
    • 2001
  • Toxicology is under challenge from several new trends in science and technology, namely computer, the Internet, genome projects, genomic technologies, and combinatorial chemistry. These new trends will drastically change research style of toxicology. In addition to conventional uni cellular tests and animal tests using rodents, computer simulation, DNA chips (microarrays), in vivo tests using simple model organisms such as nematodesor flies become important routine screening tests. How to arrange these tests in tiers will become a new problem. Endocrine disruptors hypothesis is a good example for this kind of futuristic approach. Computer, particularly the Internet, is also enabling toxicologists and regulatory experts to collaborate more closely. The IPCS (International Program for Chemical Safety) which is ajoint project of WHO, ILO and UNEP, is a well-known international collaborative research for chemical risk assessments. The GINC project of IPCS is an effort to utilize the Internet for such collaborations. Some efforts were also made to establish regional collaboration network in East Asia under this project.

  • PDF

Natural Modulators of Estrogen Biosynthesis and Function as Chemopreventive Agents

  • Bhat, Krishna P.L.;Pezzuto, John M.
    • Archives of Pharmacal Research
    • /
    • v.24 no.6
    • /
    • pp.473-484
    • /
    • 2001
  • There is clearly a need for novel breast cancer chemopreventive agents with enhanced potency and specificity with tittle or no side effects. To this end, several new chemical moieties have been synthesized or isolated from natural sources. In this reviewal we have described some agents currently in use or under development for treatment or prevention of breast cancer, as well as our own strategies for the discovery of natural product modulators of estrogen biosynthesis and function. In particulars bioassay-guided fractionation of active plant extracts is a unique method for identifying agents with novel mechanisms of action, some of which should be useful for prevention of human cancer. Further, with the advent of combinatorial chemistry and high throughput screening, even greater progress may now be expected with natural product leads.

  • PDF

Identification of Antimicrobial Peptide Hexamers against Oral Pathogens through Rapid Screening of a Synthetic Combinatorial Peptide Library

  • Song, Je-Seon;Cho, Kyung Joo;Kim, Joungmok;Kim, Jeong Hee
    • International Journal of Oral Biology
    • /
    • v.39 no.4
    • /
    • pp.169-176
    • /
    • 2014
  • A positional scanning synthetic peptide combinatorial library (PS-SCL) was screened in order to identify antimicrobial peptides against the cariogenic oral bacteria, Streptococcus mutans. Activity against Streptococcus gordonii and Aggregatibacter actinomycetemcomitans was also examined. The library was comprised of six sub-libraries with the format $O_{(1-6)}XXXXX-NH_2$, where O represents one of 19 amino acids (excluding cysteine) and X represents equimolar mixture of these. Each sub-library was tested for antimicrobial activity against S. mutans and evaluated for antimicrobial activity against S. gordonii and A. actinomycetemcomitans. The effect of peptides was observed using transmission electron microscopy (TEM). Two semi-mixture peptides, RXXXXN-$NH_2$ (pep-1) and WXXXXN-$NH_2$ (pep-2), and one positioned peptide, RRRWRN-$NH_2$ (pep-3), were identified. Pep-1 and pep-2 showed significant antimicrobial activity against Gram positive bacteria (S. mutans and S. gordonii), but not against Gram negative bacteria (A. actinomycetemcomitans). However, pep-3 showed very low antimicrobial activity against all three bacteria. Pep-3 did not form an amphiphilic ${\alpha}$-helix, which is a required structure for most antimicrobial peptides. Pep-1 and pep-2 were able to disrupt the membrane of S. mutans. Small libraries of biochemically-constrained peptides can be used to generate antimicrobial peptides against S. mutans and other oral microbes. Peptides derived from such libraries may be candidate antimicrobial agents for the treatment of oral microorganisms.

Combinatorial Fine-Tuning of Phospholipase D Expression by Bacillus subtilis WB600 for the Production of Phosphatidylserine

  • Huang, Tingting;Lv, Xueqin;Li, Jianghua;Shin, Hyun-dong;Du, Guocheng;Liu, Long
    • Journal of Microbiology and Biotechnology
    • /
    • v.28 no.12
    • /
    • pp.2046-2056
    • /
    • 2018
  • Phospholipase D has great commercial value due to its transphosphatidylation products that can be used in the food and medicine industries. In order to construct a strain for use in the production of PLD, we employed a series of combinatorial strategies to increase PLD expression in Bacillus subtilis WB600. These strategies included screening of signal peptides, selection of different plasmids, and optimization of the sequences of the ribosome-binding site (RBS) and the spacer region. We found that using the signal peptide amyE results in the highest extracellular PLD activity (11.3 U/ml) and in a PLD expression level 5.27-fold higher than when the endogenous signal peptide is used. Furthermore, the strain harboring the recombinant expression plasmid pMA0911-PLD-amyE-his produced PLD with activity enhanced by 69.03% (19.1 U/ml). We then used the online tool \RBS Calculator v2.0 to optimize the sequences of the RBS and the spacer. Using the optimized sequences resulted in an increase in the enzyme activity by about 26.7% (24.2 U/ml). In addition, we found through a transfer experiment that the retention rate of the recombinant plasmid after 5 generations was still 100%. The final product, phosphatidylserine (PS), was successfully detected, with transphosphatidylation selectivity at 74.6%. This is similar to the values for the original producer.