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Effect of Monomers in Vinyl Urethane Macromonomers on Dispersion Polymerization of Polystyrene
( Kangseok Lee ),( Sang Eun Shim ) 한국고무학회 2016 엘라스토머 및 콤포지트 Vol.51 No.2
The four different vinyl monomers in the reaction of isocyanate-terminated polyurethane prepolymer were used for the preparation of macromonomers and successfully employed in the dispersion polymerization of styrene. The chemical structures of vinyl monomer in macromonomers influenced on the polystyrene particle characteristics, such as the conversion, weight average molecular weights (Mw), polydispersity index (PDI), weight average diameter (Dw), and uniformity. The conversion of polystyrene increased with amounts of methyl group in vinyl monomer. Also the uniformity of polystyrene particles increased with amounts of methyl group in vinyl monomer.
Regulator of ribonuclease activity modulates the pathogenicity of Vibrio vulnificus
Lee Jaejin,Shin Eunkyoung,Park Jaeyeong,이민호,Lee Kangseok 한국미생물학회 2021 The journal of microbiology Vol.59 No.12
RraA, a protein regulator of RNase E activity, plays a unique role in modulating the mRNA abundance in Escherichia coli. The marine pathogenic bacterium Vibrio vulnificus also possesses homologs of RNase E (VvRNase E) and RraA (VvRraA1 and VvRraA2). However, their physiological roles have not yet been investigated. In this study, we demonstrated that VvRraA1 expression levels affect the pathogenicity of V. vulnificus. Compared to the wild-type strain, the VvrraA1-deleted strain (ΔVvrraA1) showed decreased motility, invasiveness, biofilm formation ability as well as virulence in mice; these phenotypic changes of ΔVvrraA1 were restored by the exogenous expression of VvrraA1. Transcriptomic analysis indicated that VvRraA1 expression levels affect the abundance of a large number of mRNA species. Among them, the halflives of mRNA species encoding virulence factors (e.g., smcR and htpG) that have been previously shown to affect VvrraA1 expression-dependent phenotypes were positively correlated with VvrraA1 expression levels. These findings suggest that VvRraA1 modulates the pathogenicity of V. vulnificus by regulating the abundance of a subset of mRNA species.
Lee, Jaejin,Kim, Dae-Jun,Yeom, Ji-Hyun,Lee, Kangseok Springer-Verlag 2017 Current microbiology Vol.74 No.9
<P>Synthesis of the flagellar apparatus in Escherichia coli is mediated via complex regulatory pathways. A previous study indicated that the protein encoded by the biofilm-dependent modulation (bdm) gene is linked closely with a regulatory pathway for flagellar assembly. However, the specific role of Bdm in flagellar biogenesis remains unknown. Herein, we showed that Bdm interacts with FlgM and inhibits its function as an anti-sigma 28 factor, which induces the transcription of flagellar late-class genes in E. coli. In addition, we observed that deletion of the yddX gene, a potential Salmonella enterica serovar Typhimurium homolog of bdm, also resulted in downregulation of flagellar late-class genes and in the formation of short flagella, leading to decreased virulence in mice. The expression levels of late-class flagellar genes in yddX-deleted S. Typhimurium cells were restored to those of the wild type when either E. coli bdm or S. Typhimurium yddX was expressed exogenously. These results suggest that Bdm-mediated regulation of flagellar assembly is a conserved regulatory pathway in those members of the Enterobacteriaceae family whose genomes show the existence of homologs of bdm.</P>
Synthesis of Alkoxy Modified Silicone Using Alkali Catalyst
( Kangseok Lee ),( Sang Eun Shim ) 한국고무학회 2016 엘라스토머 및 콤포지트 Vol.51 No.2
Alkoxy modified silicone (PAMS) was synthesized from hydroxyl-terminated polydimethylsiloxane (OHPDMS) and vinyltrimethoxysilane (VTMO) under alkali catalyst (NaOH and KOH) at room temperature (25℃) via condensation polymerization. Then, the structural verification of the synthesized PAMS was confirmed using 1H-NMR and FTIR spectroscopy. The reaction rate of PAMSs was studied in terms of the concentration variation of alkali catalyst. The reaction rate increased with the concentration of alkali catalyst, but no correlation between conversion and concentration of alkali catalyst was observed.
Development of DNA aptamers specific for small therapeutic peptides using a modified SELEX method
Lee Jaemin,Ryu Minkyung,Bae Dayeong,Kim Hong-Man,Eyun Seong-il,Bae Jeehyeon,Lee Kangseok 한국미생물학회 2022 The journal of microbiology Vol.60 No.7
Aptamers are short single-stranded DNA or RNA oligonucleotides capable of binding with high affinity and specificity to target molecules. Because of their durability and ease of synthesis, aptamers are used in a wide range of biomedical fields, including the diagnosis of diseases and targeted delivery of therapeutic agents. The aptamers were selected using a process called systematic evolution of ligands by exponential enrichment (SELEX), which has been improved for various research purposes since its development in 1990. In this protocol, we describe a modified SELEX method that rapidly produces high aptamer screening yields using two types of magnetic beads. Using this method, we isolated an aptamer that specifically binds to an antimicrobial peptide. We suggest that by conjugating a small therapeutic-specific aptamer to a gold nanoparticle-based delivery system, which enhances the stability and intracellular delivery of peptides, aptamers selected by our method can be used for the development of therapeutic agents utilizing small therapeutic peptides.