• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.31-31
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• 2002

$\alpha$$_1$-Antitrypsin is a member of the serine protease inhibitor (serpin) family that share a common tertiary structure. The reactive site loop (RSL) of serpins is exposed at one end of the molecule for protease binding. Upon cleavage by a target protease, the RSL is inserted into the major $\beta$-sheet A, which is a necessary process for formation of a tight inhibitory complex.(omitted)

• Proceedings of the Korean Biophysical Society Conference
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• 2001.06a
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• pp.33-33
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• 2001

Bacterial Δ$\^$5/-3-ketosteroid isomerase (KSI) is one of the most proficient enzymes catalyzing the isomerization of a variety of Δ$\^$5/-ketosteroids to Δ$^4$-ketosteroids at a diffusion-controlled rate. Because of the simplicity of the reaction, the enzyme mechanism has been intensively studied as a prototype to understand enzyme-catalyzed C-H bond cleavage.(omitted)

• The Korean Journal of Zoology
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• v.25 no.3
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• pp.107-114
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• 1982

A combination of ultraviolet irradiation and egg rotation was applied to Korean frogs to study the mechanisms of the establishment of the dorsal-ventral polarity. Rotation of the uncleaved egg was capable of preventing the characteristic syndromes associated with UV irradiation. As well, brief rotation of the egg before cleavage relocates the site of dorsal lip to a novel location in the embryo at gastrula stage. That is, the dorsal lip appeared on the opposite side to gravity at the rotation of the egg. Above results were discussed with the informations obtained from other anuran and urodele species, and were interpreted in terms of regulating mechanisms for early embryogenesis.

• Bulletin of the Korean Chemical Society
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• v.17 no.1
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• pp.24-28
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• 1996

A procedure is described for the synthesis of the title compound via phosphotriester intermediates. The preparation of $R_p$ and $S_p$ diastereomeric dinucleotide of d[Cp(S)T] was performed by the condensation of the protected deoxycytidine, the protected thymidine, 2,5-dichlorophenylphosphorodichloridothioate and 1-hydroxybenzotriazole in THF. Their designation of configuration at phosphorus as $R_p$ and $S_p$ follows from anaylsis of ${31}^P$ NMR spectroscopy and reverse-phase HPLC and the stereospecificity in the hydrolysis catalyzed by Nuclease S1 and snake venom phosphodiesterase. Diastereomerically pure $R_p$ and $S_p$ d[Cp(S)T] were utilized to synthesize oligonucleotides containing the XhoI recognition sequence with a phosphorothioate group at the cleavage site.

• BMB Reports
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• v.53 no.12
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• pp.611-621
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• 2020

Bacterial endoribonuclease toxins belong to a protein family that inhibits bacterial growth by degrading mRNA or rRNA sequences. The toxin genes are organized in pairs with its cognate antitoxins in the chromosome and thus the activities of the toxins are antagonized by antitoxin proteins or RNAs during active translation. In response to a variety of cellular stresses, the endoribonuclease toxins appear to be released from antitoxin molecules via proteolytic cleavage of antitoxin proteins or preferential degradation of antitoxin RNAs and cleave a diverse range of mRNA or rRNA sequences in a sequence-specific or codon-specific manner, resulting in various biological phenomena such as antibiotic tolerance and persister cell formation. Given that substrate specificity of each endoribonuclease toxin is determined by its structure and the composition of active site residues, we summarize the biology, structure, and substrate specificity of the updated bacterial endoribonuclease toxins.

• Journal of Animal Reproduction and Biotechnology
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• v.37 no.1
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• pp.62-66
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• 2022

To date, the development of anticancer drugs has been conducted using two-dimensional (2D) cell culture systems. However, since cancer cells in the body are generated and developed in three-dimensional (3D) microenvironments, the use of 2D anticancer drug screening can make it difficult to accurately evaluate the anticancer effects of drug candidates. Therefore, as a step towards developing a cancer cell-friendly 3D microenvironment based on a combination of vinylsulfone-functionalized polyethylene glycol (PEG-VS) with dicysteine-containing crosslinker peptides with an intervening matrix metalloproteinase (MMP)-specific cleavage site, the types of MMPs secreted from human hepatocarcinoma HepG2 cells, a representative cancer cell, were analyzed transcriptionally and translationally. MMP3 was confirmed to be the most highly expressed protease secreted by HepG2 cells. This knowledge will be important in the design of a crosslinker necessary for the construction of PEG-based hydrogels customized for the 3D culture of HepG2 cells.

• International Journal of Industrial Entomology and Biomaterials
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• v.15 no.1
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• pp.83-85
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• 2007

A glycine and proline-rich antibacterial protein was cloned from larvae of a beetle, Protaetia brevitarsis. The DNAs encoded a deduced propeptide of 127 amino acid residues with predicted molecular weight of 14.0 kDa and PI of 7.89. Structural analysis of this protein indicated the presence of a recognition sequence for the cleavage site within the constitutive secretory pathway(Arg-Xaa-Lys/Arg-Arg), suggesting that mature portion(72 amino acid residues) is produced by cleavage of signal peptide and propeptide from 127 amino-acid-long precursor protein. Mature portion sequence of this protein showed 72% similarity to that of Oryctes rhinoceros Rhinocerosin and 91% to that of Holotrichia diomphalia holotricin 2. The mRNA expression was reached the highest level at 4 hrs after E. coli injection and then declined gradually.

• Biomedical Science Letters
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• v.16 no.3
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• pp.201-206
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• 2010

In order to develop procedures for the rapid isolation of recombinant sugar transporter in functional form from away from the endogenous insect cell transporter, gene fusion techniques were exploited. Briefly, BamH1-digested human HepG2 type glucose transport protein cDNA was first cloned into a transfer vector pBlueBacHis, containing a tract of six histidine residues. Recombinant baculoviruses including the human cDNA were then generated by allelic exchange following transfection of insect cells with wild-type BaculoGold virus DNA and the recombinant transfer vector. Plaque assay was then performed to obtain and purify recombinant viruses expressing the human transport protein. All the cell samples that had been infected with viruses from the several blue plaques exhibited a positive reaction in the immnuassay, demonstrating expression of the glucose transport protein. In contrast, no color development in the immunoassay was observed for cells infected with the wild-type virus or no virus. Immunoblot analysis showed that a major immunoreactive band of apparent Mr 43,000~44,000 was evident in the lysate from cells infected with the recombinant baculovirus. Following expression of the recombinant fusion protein with the metal-binding domain and enterokinase cleavage site, the fusion protein was recovered by competition with imidizole using immobilized metal charged resin. The leader peptide was then removed from the fusion protein by cleavage with porcine enterokinase. Final separation of the recombinant protein of the interest was achieved by passage over $Ni^{2+}$-charged resin under binding conditions. The expressed transport protein bound cytochalasin B and demonstrated a functional similarity to its human counterpart.

• BMB Reports
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• v.39 no.3
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• pp.270-277
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• 2006

Helices 4 and 5 of the Bacillus thuringiensis Cry4Ba $\delta$-endotoxin have been shown to be important determinants for mosquito-larvicidal activity, likely being involved in membrane-pore formation. In this study, the Cry4Ba mutant protein containing an additional engineered tryptic cleavage site was used to produce the $\alpha4$-$\alpha5$ hairpin peptide by an efficient alternative strategy. Upon solubilization of toxin inclusions expressed in Escherichia coli and subsequent digestion with trypsin, the 130-kDa mutant protoxin was processed to protease-resistant fragments of ca. 47, 10 and 7 kDa. The 7-kDa fragment was identified as the $\alpha4$-loop-$\alpha5$ hairpin via N-terminal sequencing and mass spectrometry, and was successfully purified by size-exclusion FPLC and reversed-phase HPLC. Using circular dichroism spectroscopy, the 7-kDa peptide was found to exist predominantly as an $\alpha$-helical structure. Membrane perturbation studies by using fluorimetric calcein-release assays revealed that the 7-kDa helical hairpin is highly active against unilamellar liposomes compared with the 65-kDa activated full-length toxin. These results directly support the role of the $\alpha4$-loop-$\alpha5$ hairpin in membrane perturbation and pore formation of the full-length Cry4Ba toxin.

• Journal of Microbiology and Biotechnology
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• v.24 no.2
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• pp.160-167
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• 2014

Oligopeptidase B (OpdB) is a serine peptidase widespread among bacteria and protozoa that has emerged as a virulence factor despite its function has not yet been precisely established. By using an OpdB-overexpressing Escherichia coli strain, we found that the overexpressed peptidase makes the bacterial cells specifically less susceptible to several proline-rich antimicrobial peptides known to penetrate into the bacterial cytosol, and that its level of activity directly correlates with the degree of resistance. We established that E. coli OpdB can efficiently hydrolyze in vitro cationic antimicrobial peptides up to 30 residues in length, even though they contained several prolines, shortening them to inactive fragments. Two consecutive basic residues are a preferred cleavage site for the peptidase. In the case of a single basic residue, there is no cleavage if proline residues are present in the $P_1$ and $P_2$ positions. These results also indicate that cytosolic peptidases may cause resistance to antimicrobial peptides that have an intracellular mechanism of action, such as the proline-rich peptides, and may contribute to define the substrate specificity of the E. coli OpdB.