• Molecules and Cells
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• v.19 no.1
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• pp.54-59
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• 2005

Deoxyribonuclease I (DNase I) is a divalent cation dependent endonuclease and thought to be a significant barrier to effective gene delivery. The only known DNase I-specific inhibitor is monomeric actin which acts by forming a 1:1 complex with DNase I. Its use, however, is restricted because of tendency to polymerize under certain conditions. We screened two random phage peptide libraries of complexity $10^8$ and $10^9$ for DNase I binders as candidates for DNase I inhibitors. A number of DNase I-binding peptide sequences were identified. When these peptides were expressed as fusion proteins with Escherichia coli maltose binding protein, they inhibited the actin-DNase I interaction ($IC_{50}=0.1-0.7{\mu}M$) and DNA degradation by DNase I ($IC_{50}=0.8-8{\mu}M$). Plasmid protection activity in the presence of DNase I was also observed with the fusion proteins. These peptides have the potential to be a useful adjuvant for gene therapy using naked DNA.

• YAKHAK HOEJI
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• v.37 no.2
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• pp.149-157
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• 1993

Protein methylase inhibitor which is a modulator of biological methylation has been purified and characterized from porcine liver soluble fraction by cell fractionation, Sephadex G25 chromatography, reverse phase HPLC, size exclusion HPLC. The results are summarized as follows. 1) The purified inhibitor shows apparent homogeneity, as judged by HPLC. 2) A molecular weight of the purified inhibitor which is composed of 18 amino acid residues is about 1,400 daltons. 3) A single absorption peak of ultraviolet spectrum was observed at 260nm. 4) The inhibitor was not inactivated by heating at $100^{\circ}C$ until 60min. and its activity was not influenced by treatment with digestive enzymes, such as trypsin, pepsin, pronase, chymotrypin, lysozyme, DNase, and RNase. 5) The purified inhibitor inhibited protein rnethylase I, II, III and phospholipid methyltransferase activities. 6) The purified inhibitor inhibited noncompetitively protein methylase II from porcine liver, spleen, and testis. 7) The $K_{i}$ values for protein methylase II from porcine liver, spleen, and testis were 300nM, 250nM, 297nM, respectively.

• Journal of Microbiology
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• v.33 no.3
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• pp.191-195
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• 1995

IciA protein has been shown as an inhibitor for the initiation of E. coli chromosomal DNA replication at oriC. IciA protein binds the AT-rich region in oriC and then blocks the initiation of chromosomal DNA replication. Two binding sites for IciA protein were identified in dnaA gene, encoding the initiator for the E. coli chromosomal replication, promoter region by gel-shift assay and DNase I footprinting, One, named as IciA site I, is located upstream of the dnaA promoter 1P. The other, named as IciA site II, is located downstream of the dnaA promoter 2P. The sequence comparison of the regions protected from the DNase I cleavage did not result in a clear consensus sequence for the binding of IciA protein, suggesting that IciA protein may be a member of multimeric complex dsDNA binding proteins. This study provided information about the binding mode of IciA protein. Even though the IciA site II and IciA binding site in oriC seem to be composed of two IciA binding units, one binding unit is likely enough to cause the binding of IciA protein to the IciA site I. The binding of IciA protein to the dna4 promoter implies that IciA protein may involve not only the control of the initiation of chromosomal DNA replication but also the control of the dna4 gene expression.

• Journal of Life Science
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• v.22 no.6
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• pp.815-822
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• 2012

Piceatannol (trans-3,4,3',5'-tetrahydroxystilbene), a natural stilbene, is an analogue of resveratrol. Although recent experimental data have revealed the health benefit potency of piceatannol, the molecular mechanisms underlying the anti-cancer activity have not yet been studied in detail. In the present study, the further possible mechanisms by which piceatannol exerts its pro-apoptotic action in cultured human lung cancer A549 cells were investigated. Exposure of A549 cells to piceatannol resulted in growth inhibition and induction of apoptosis. Apoptosis induction of A549 cells by piceatannol showed correlation with proteolytic activation of caspase-3, -8, and -9, and concomitant degradation of activated caspase-3 target proteins such as poly (ADP-ribose) polymerase, phospholipase C-${\gamma}1$, ${\beta}$-catenin, and Inhibitor caspase-activated DNase. The increase in apoptosis by piceatannol treatment was also associated with an increase of pro-apoptotic Bax expression and decrease of anti-apoptotic Bcl-2 and Bcl-xL expression, and caused down-regulation of the inhibitor of apoptosis protein family members and up-regulation of Fas and Fas legend. In addition, piceatannol treatment markedly inhibited the expression of mRNA and proteins of inducible nitric oxide (NO) synthase, and the levels of NO production were progressively down-regulated by piceatannol treatment in a dose-dependent fashion. The results indicate that piceatannol may have therapeutic potential against human gastric cancer cells.