• Journal of Microbiology and Biotechnology
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• v.22 no.11
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• pp.1588-1590
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• 2012

We compared the mRNA expression profile of the Harmonia axyridis larvae that were either untreated or treated with LPS. The extracted mRNAs were subjected to ACP RT-PCR analysis using a combination of arbitrary primers and oligo (dT) primer. Among the 47 DEGs differentially expressed, we identified a cDNA showing homology with defensin-like antibacterial peptide. The cDNA showed a putative 32-residue signal sequence and a 50-residue mature peptide named harmoniasin. We also investigated the antibacterial activity of the harmoniasin analog, which exhibited potent antibacterial activities against Gramnegative and -positive bacteria strains and it also evidenced no hemolytic activity.

• BMB Reports
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• v.30 no.4
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• pp.299-301
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• 1997

The asialoglycoprotein receptor (ASGPR) was the first described mammalian lectin that mediates the specific binding and internalization of galactose/N-acetylgalactosamine-terminating glycoproteins by hepatic parenchymal cells. H1 and H2 are known as essential subunits of the functional ASGPR. There were close similarities in ASGPR H2 subunits between cultured cell line HepG2 and normal human liver cells including identical sequences at both termini. It was therefore expected that there may be some similarities between the subunits from normal liver cells and fetal liver cells. The two subunits of human fetal liver ASGPR. designated FL-H1 and FL-H2. were cloned from cDNA library by peR and the sequences were compared with the known HI and H2 sequences of HepG2, and the H1 sequence of nornal human liver cells. The results showed that FL-H1 was identical to H1 of HepG2. Whereas FL-H2 contains a 15-bp miniexon, but missing 57-bp at the near upstream from the membrane-spanning domain compared to H2 of HepG2 and normal human liver cells indicating that FL-H2 resulted from a differential splicing compared to HepG2 and normal liver cells.

• Korean Journal of Plant Tissue Culture
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• v.25 no.2
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• pp.109-113
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• 1998

In this study we tried to transform an antimicrobial peptide gene (Shiva) under the promoter of tomato phenylalanine ammonia-lyase (tPAL5) into tobacco and potato plants. Antimicrobial peptide gene was isolated originally from giant silk moth (Hyalophora cecropia) and modified ie nucleotide sequence to increase antimicrobial activity. Transgenic tobacco plants were regenerated and their seeds were tested on the media containing kanamycin (500 mg/L). The results of PCR amplification and genomic Southern blot hybridization confirmed the integration of construct (tPAL5 promoter-Shiva-NOS-GUS-NOS) into chromosome. We observed that one of the transgenic tobacco plants showed chromosome rearrangement when integrated. In case of potato transformation, the efficiency of regeneration was maximized at the medium containing Zeatin 2mg/L, NAA 0.01mg/L, GA$_3$ 0.1mg/L. We also observed the high expression of GUS (${\beta}$-glucuronidase) enzyme which was located next to the terminator sequence of nopaline synthase gene (NOS) in the vascular tissue of stem, leaves of transgenic potatoes. This result suggested that a short sequence of Shiva gene (120 bp) and NOS terminator sequence might be served as a leader sequence of transcript when translated.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.8
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• pp.1124-1129
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• 2005

Functional activities of low molecular weight substances purified from pepsin hydrolysates of four different seaweeds; Costaria costata, Enteromorpha prolifera, Grateloupia filicina and Porphyra tenera, were inves-tigated. Each pepsin hydrolysate of Costaria costata, Enteromorpha prolifera, and Grateloupia filicina resulted in three peptide peaks on Bio-Rad P2 gel chromatography pattern, while that of Porphyra tenera showed 2 peaks. Peak 1 of Porphyra tenera showed the highest antioxidative activity followed by peak 2 of Porphyra tenera and peak 2 of Costaria costata in order Peak 1 of Porphyra tenera showed the highest ACE inhibitory activity followed by peak 3 and peak 2 of Enteromorpha prolifera in order. Peak 1 and peak 2 of Porphyra tenera, and peak 2 of Enteromorpha prolifera showed the highest antityrosinase activity followed by peak 3 of Enteromorpha prolifera. Peak 1 of Enteromorpha prolifera showed the highest antitumor activity followed by peak 2 of Costaria costata, peak 3 of Enteromorpha prolifera, and peak 3 of Grateloupia filicina in order. Porphyra tenera showed the highest functional activities, which is thought to be due to its high protein content. Structure and amino acid sequence of low molecular weight peptide of Porphyra tenera should be analyzed in the further study.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1527-1534
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• 2010

The conventional peptide modification process of guanidination, in which the amino groups of lysine residues are converted to guanidino groups using O-methylisourea to create more basic homoarginine residues, is often used to improve the signal intensity of lysine-containing peptides in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Here, we used three different protease enzymes (trypsin, Lys-C, and Glu-C) to evaluate the effects of guanidination on the MS signals of two enzymatically digested proteins. Horse heart myoglobin and bovine serum albumin were guanidinated either before or after digestion with trypsin, Lys-C, or Glu-C. The resulting peptides were subjected to MALDI-MS, and signal intensities and sequence coverage were systematically evaluated for each digest. Guanidination prior to Glu-C digestion improved sequence coverage for both proteins. For myoglobin, guanidination before enzymatic digestion with trypsin or Lys-C also enhanced sequence coverage, but guanidination after enzymatic digestion enhanced sequence coverage only with Lys-C. For albumin, guanidination either before or after Glu-C digestion increased sequence coverage, whereas pre- or post-digestion guanidination decreased sequence coverage with trypsin and Lys-C. The amino acid composition of a protein appears to be the major factor determining whether guanidination will enhance its MALDI-MS sequence coverage.

• The Korean Journal of Food And Nutrition
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• v.4 no.2
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• pp.161-166
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• 1991

The blocked N-terminus and N-terminal sequence of soybean B-amylase were aetermined by analyzing the acidic peptides derived on peptic digestion of the enzyme. The acidic peptides were separated from the digest on a Dowex 50$\times$2 column(1X5cm) and purified by reversed phase-high performance liquid chromatography(RP-HPLC). The major acidic peptide, PEP-1, was a heptapeptlde. The N-terminal 7 amino acid sequence of soybean B-amylase was deduced to be acetyl-Ala-Thf-Ser-Asp-Ser-Asn-Met- from the results of sequence analysis of PEP-1 and amino acid analysis of other acidic peptides.

• International Journal of Industrial Entomology and Biomaterials
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• v.17 no.1
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• pp.131-135
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• 2008

A cDNA encoding a defensin-like peptide (Protaetiamycine) from the larvae of a beetle, Protaetia brevitarsis was cloned. The DNAs encoded the deduced propeptide of 79 amino acid residues with the predicted molecular weight of 8.4 kDa and PI of 8.24. Overall amino acid sequence of this protein has 39% similarity to that of Rhodnius prolixus defensin, 43% similarity to that of Acalolepta luxuriosa defensin, and 72% similarity to that of Oryctes rhinoceros defensin, suggesting that this gene is an insect defensin. In an attempt to apply the anti-bacterial peptide to the development of therapeutic agents, a 12-mer peptide amidated at its C-terminus, ACAAHCLAIGRG-$NH_2$ (Ala55-Lys66-$NH_2$, 12Pbn) was synthesized. This peptide showed some antifungal activity against Candida albicans. To increase antifungal activity, six 9-mer peptides were synthesized by modifying amino acid sequences of 12Pbn fragment. Among these peptides, 9Pbm3-9Pbm6 exhibited strong activity compared with Cecropin B and mellitin.

• KIISE Transactions on Computing Practices
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• v.22 no.1
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• pp.56-60
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• 2016

Peptide identification in tandem mass spectrometry is usually done by searching the spectra against target databases consisting of reference protein sequences. To control false discovery rates for high-confidence peptide identification, spectra are also searched against decoy databases constructed by permuting reference protein sequences. In this case, a peptide of the same sequence could be included in both the target and the decoy databases or multiple entries of a same peptide could exist in the decoy database. These phenomena make the protein identification problem complicated. Thus, it is important to minimize the number of such redundant peptides for accurate protein identification. In this regard, we examined two popular methods for decoy database generation: 'pseudo-shuffling' and 'pseudo-reversing'. We experimented with target databases of varying sizes and investigated the effect of the maximum number of missed cleavage sites allowed in a peptide (MC), which is one of the parameters for target and decoy database generation. In our experiments, the level of redundancy in decoy databases was proportional to the target database size and the value of MC, due to the increase in the number of short peptides (7 to 10 AA). Moreover, 'pseudo-reversing' always generated decoy databases with lower levels of redundancy compared to 'pseudo-shuffling'.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.7
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• pp.1052-1061
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• 2019

Objective: This study was conducted to identify duck liver-expressed antimicrobial peptide 2 (LEAP-2) and demonstrate its antimicrobial activity against various pathogens. Methods: Tissue samples were collected from 6 to 8-week-old Pekin ducks (Anas platyrhynchos domesticus), total RNA was extracted, and cDNA was synthesized. To confirm the duck LEAP-2 transcript expression levels, quantitative real-time polymerase chain reaction was conducted. Two kinds of peptides (a linear peptide and a disulfide-type peptide) were synthesized to compare the antimicrobial activity. Then, antimicrobial activity assay and fluorescence microscopic analysis were conducted to demonstrate duck LEAP-2 bactericidal activity. Results: The duck LEAP-2 peptide sequence showed high identity with those of other avian species (>85%), as well as more than 55% of identity with mammalian sequences. LEAP-2 mRNA was highly expressed in the liver with duodenum next, and then followed by lung, spleen, bursa and jejunum and was the lowest in the muscle. Both of LEAP-2 peptides efficiently killed bacteria, although the disulfide-type LEAP-2 showed more powerful bactericidal activity. Also, gram-positive bacteria was more susceptible to duck LEAP-2 than gram-negative bacteria. Using microscopy, we confirmed that LEAP-2 peptides could kill bacteria by disrupting the bacterial cell envelope. Conclusion: Duck LEAP-2 showed its antimicrobial activity against both gram-positive and gram-negative bacteria. Disulfide bonds were important for the powerful killing effect by disrupting the bacterial cell envelope. Therefore, duck LEAP-2 can be used for effective antibiotics alternatives.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.6
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• pp.927-937
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• 2021

This study was performed to screen the antimicrobial activities of the extract from the Pacific oyster Crassostrea gigas against skin pathogens and to purify the relevant antibacterial peptide. The acidified extract showed potent antibacterial activities against gram-positive and gram-negative bacteria but showed no activity against Candida albicans and no significant cell toxicity. Among acne-causing pathogens, the acidified extract showed potent antibacterial activity only against Staphylococcus aureus, and its antibacterial activity was completely abolished by treatment with trypsin or chymotrypsin, and was inhibited by salt treatment. The acidified extract showed strong DNA-binding ability but did not show bacterial membrane permeabilizing ability. Based on antimicrobial activity screening and cytotoxic effects, a novel antibacterial peptide was purified from the acidified gill extract using solid-phase extraction, cation-exchange, and reversed-phase HPLC. The resulting peptide had a molecular weight of 4800.8 Da and showed partial sequence homology with the carbonic anhydrase 4 (CA4) protein in the hard-shelled mussel. Overall, we purified a novel antibacterial peptide, named cgCAFLP, which is related to carbonic anhydrase 4 (CA4) protein, against skin pathogens. Our results suggest that the Pacific oyster extract could be used as an additive to control some acne-related skin pathogens (S. aureus).