• Proceedings of the PSK Conference
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• 2001.10a
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• pp.238.2-238.2
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• 2001

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.356-362
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• 2010

Ceramide is important not only for the maintenance of the barrier function of the skin but also for the water-binding capacity of the stratum corneum. Although the exact role of ceramide in the human skin is not fully understood, ceramide has become a widely used ingredient in cosmetic and pharmaceutical industries. Compared with other microorganisms, yeast is more suitable for the production of ceramide because yeast grows fast and is non-toxic. However, production of ceramide from yeast has not been widely studied and most work in this area has been carried out using Saccharomyces cerevisiae. Regulating the genes that are involved in sphingolipid synthesis is necessary to increase ceramide production. In this study, we investigated the effect of the genes involved in the synthesis of ceramide, lcb1, lcb2, tsc10, lac1, lag1, and sur2, on ceramide production levels. The genes were cloned into pYES2 high copy number vectors. S. cerevisiae was cultivated on YPDG medium at $30^{\circ}C$. Ceramide was purified from the cell extracts by solvent extraction and the ceramide content was analyzed by HPLC using ELSD. The maximum production of ceramide (9.8 mg ceramide/g cell) was obtained when the tsc10 gene was amplified by the pYES2 vector. Real-time RT-PCR analysis showed that the increase in ceramide content was proportional to the increase in the tsc10 gene expression level, which was 4.56 times higher than that of the control strain.

• Microbiology and Biotechnology Letters
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• v.19 no.3
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• pp.242-247
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• 1991

- Since steroid $\Delta^1$-dehydrogenase synthesis has been known to be inducible, the mechanism of the enzyme induction of Arthrobacter simplex IAM 1660 was investigated. Among various steroids tested for inducers, hydrocortisone was the most effective inducer when hydrocortisone was used as a substrate for steroid $\Delta^1$-dehydrogenase. Steroid $\Delta^1$-dehydrogenase synthesis was effectively induced by progesterone, prednisolone and androstenedione, while the enzyme was less induced by cholesterol and not by phytosterols. The results suggest that the presence of 3-keto group and short side chain of steroids are the favorable factors for the induction of the $\Delta^1$-dehydrogenase synthesis. The enzyme was induced at the highest level when hydrocortisone was added at early log phase to the concentration of 0.01% of the culture and the culture was grown for 15 hours.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.713-714
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• 2005

• Proceedings of the Korean Vacuum Society Conference
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• 2006.08a
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• pp.58-58
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• 2006

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.3
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• pp.5-13
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• 2023

In this study, a comparative study is conducted on the synthesis methods for silica nanoparticle employing the silicon sludge waste generated from the semiconductor manufacturing processes. Specifically, acid-washed silicon sludge wastes with no impurities are employed as the precursors of sol-gel and hydrothermal methods for silica nanoparticles preparation. The morphologies and properties of silica nanoparticles synthesized via two synthetic methods are examined by various analysis methods. As a result, silica nanoparticles from the sol-gel method are fabricated with high purity and uniform shape, while the hydrothermal method exhibits advantages in yield and ease of synthetic process. This comparative study offers detailed experimental results on the two synthetic methods for silica nanoparticle synthesis, which may contribute to the establishment of manufacturing high-value materials using the by-products generated in the semiconductor process.

• Biomolecules & Therapeutics
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• v.31 no.2
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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.

• Korean Journal of Biological Psychiatry
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• v.5 no.2
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• pp.219-226
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• 1998

Cytosine arabinoside(AraC) inhibits DNA synthesis and ${\beta}$-DNA polymerase, an enzyme involved in DNA repair. This, a potent antimitotic agent, is clinically used as an anticancer drug with side effect of severe neurotoxicity. Earlier reports suggested that inhibition of neuronal survival by AraC in sympathetic neuron may be due to the inhibition of a 2'-deoxycytidine-dependent process that is independent of DNA synthesis or repair and AraC induced a signal that is triggers a cascade of new mRNA and protein synthesis, leading to apoptotic cell death in cultured cerebellar granule cells. The present study would suggest whether caspase family(ICE/CED-3-like protease) involved in AraC-induced apoptosis pathway of PC12 cells. It was observed that treatment of PC12 cells with AraC led to decrease of viability by MTT assay and morphology changes, which did not suggest that AraC induced apoptosis in PC12 cells. The mRNA of caspase-1/caspase-3 were expressed in PC12 cells constitutively, and AraC did not activate caspase family. These results suggest that caspase-1/caspase-3 may not be required for AraC-induced cell death pathway in PC12 cells.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.5
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• pp.420-424
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• 2006

A simple method for depleting E. coliS30 extracts of endogenous tRNA has been developed. An $ethanolamine-Sepharose^{(R)}$ column equilibrated with water selectively captured the tRNA molecules in E. coli S30 extracts. As a result, S30 extracts filtered through this column became completely dependent upon the addition of exogenous tRNA to mediate cell-free protein synthesis reactions. We anticipate that the procedures developed and described will be particularly useful for in vitro suppression reaction studies designed to introduce unnatural amino acids into protein molecules.

• Journal of Microbiology and Biotechnology
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• v.17 no.4
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• pp.579-585
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• 2007

Formation of inclusion bodies is usually observed when foreign proteins are overexpressed in E. coli. The formation of inclusion bodies might be prevented by lowering the rate of protein synthesis, and appropriate regulation of the protein expression rate may lead to the soluble expression. In this study, human growth hormone (rhGH) was expressed in a soluble form by slowing down the protein synthesis rate, which was controlled in the transcriptional and translational levels. The transcriptional level was controlled by the regulation of the amount of RNA polymerase specific to the promoter in front of the rhGH gene. For lowering the rate of translation, the T7 transcription terminator-deleted vector was used to synthesize the longer mRNA of the target gene because the longer mRNA is expected to reduce the availability of tree ribosomes. In both methods, the percentage of soluble expression increased when the expression rate slowed down, and more than 93% of rhGH expressed was a soluble form in the T7 transcription terminator-deleted expression system.