• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1534-1535
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• 2007

This paper describes a novel microfluidic device with a microfabricated electrospray source for a sheathless electrospray ionization interface to a mass spectrometer. This electrospray ionization-mass spectrometry (ESI-MS) device consists of a triangular-shaped metal emitter, allowing the generation of an efficient electrospray for peptide detection, and microfluidic channels monolithically in a glass microchip. The performance of the proposed interface was evaluated by opimizing its experimental condition and spraying standard peptides. The spraying has high signal strength and stability, with a relative standard deviation of 2.9% and singly-charged and doubly-charged peaks of the peptides were successfully detected. The metal emitter source showed a good performance to be comparable to commercially available emitters in signal strength and stability.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.5
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• pp.745-751
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• 2003

This study was carried out to investigate whether peptide produced from wheat protein by enzyme hydrolysis can be used as a natural antimicrobial agent. Antimicrobial peptide was obtained from wheat protein hydrolyzed by 7 of pretense. The produced antimicrobial peptide was purified through ultrafiltration, membrane filtration and HPLC and molecular weight and amino acid sequence of the purified antimicrobial peptide were determined. Among hydrolysate produced from wheat protein by 7 of protease, antimicrobial activity was observed for the peptide obtained from Asp. saito protease. The Asp. saito protease did produce antimicrobial hydrolysate showing the highest antimicrobial activity at reaction condition of 37$^{\circ}C$ and pH 6.0, but not at reaction condition above 5$0^{\circ}C$. Wheat protein hydrolysate was fractionated by membrane filtration and showed antimicrobial activity between molecular weight 1,000~3,000. The antimicrobial activity fraction obtained by membrane filtration was separated through HPLC and showed antimicrobial activity in the peak of retention time 31.1~31.8 min. We could convince this hydrolysate as heat-stable peptide since antimicrobial activity was maintained after treated with heat for 15 min at 121$^{\circ}C$. Molecular weight of antimicrobial peptide identified by MALDI-mass was 1,633. Amino acid sequence of antimicrobial peptide was cysteine, glycine, prolin, prolin, prolin, valine, valine, alanine, alanine and arginine.

• Polymer(Korea)
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• v.38 no.4
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• pp.550-556
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• 2014

Recently, the peptide(or protein)-polymer hybrid materials (PPs) were sought in many research areas as potential building blocks for assembling nanostructures in selective solvents. In PPs, the facile routes of preparing well-defined peptide-polymer bio-conjugates and their specific activities in various applications are important issues. Our strategy to prepare the peptide-polymer hybrid materials was to combine atom transfer radical polymerization (ATRP) method with solid phase peptide synthesis. The standard solid phase peptide synthesis method was employed to prepare the PYGK (proline-tyrosine-glycine-lysine) peptide. PYGK is an analogue peptide, PFGK (proline-phenylalanine-glycine-lysine), which interacted with plasminogen in fibrinolysis. The peptide and the peptide-initiator were characterized with MALDI-TOF mass spectrometry and $^1H$ NMR spectrometer. The peptide-polymer, pSt-PYGK was characterized by GPC, IR, $^1H$ NMR spectrometer and TLC. Spherical micellar aggregates were determined by TEM and SEM. Current synthesis methodology suggested opportunities to create the well-defined peptide-polymer hybrid materials with specific binding activity.

• Korean Journal of Agricultural Science
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• v.29 no.2
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• pp.78-90
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• 2002

This study was carried out to investigate whether peptide produced from wheat protein by enzyme hydrolysis can be used as a natural antimicrobial agent. Antimicrobial peptide was obtained from wheat protein by protease of 7 species. The produced antimicrobial peptide was purified through ultrafiltration, membrane filtration and HPLC, and molecular weight and amino acid sequence of the purified antimicrobial peptide were determined. Among hydrolysate produced from wheat protein by protease of 7 species, antimicrobial activity was observed for the peptide obtained from Asp. saito protease. The Asp. saito protease did production antimicrobial hydrolysate showing the highest antimicrobial activity at reaction condition of $37^{\circ}C$ and pH 6.0, but not at reaction condition above $50^{\circ}C$. Wheat protein hydrolysate was fractionated by membrane filtration and showed antimicrobial activity between molecular weight 1,000 - 3,000. The antimicrobial activity fraction obtained by membrane filtration was separated through HPLC and showed antimicrobial activity in the peak of retention time 31.1 - 31.8 min. Since after wheat protein protease hydrolysate was heated during 15 min at $121^{\circ}C$, antimicrobial activity was maintained, we could be conviction as heat-stable peptide. Molecular weight of antimicrobial peptide identified by MALDI-mass was 1,633. Amino acid sequence of antimicrobial peptide was cysteine, glycine, prolin, prolin, prolin, valine, valine, alanine, alanine and arginine.

• Food Science of Animal Resources
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• v.34 no.5
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• pp.656-664
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• 2014

The purpose of this study was to analyze myosin heavy chain (MHC) isoforms in bovine longissimus thoracis (LT) muscle by liquid chromatography (LC) and mass spectrometry (MS). LT muscles taken from Hanwoo (Korean native cattle) steer (n=3) used to separate myosin bands by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The peptide queries were obtained from the myosin bands by LC-MS/MS analysis following in-gel digestion with trypsin. A total of 33 and 43 queries were identified as common and unique peptides, respectively, of MHC isoforms (individual ions scores >43 indicate identity or extensive homology, p<0.05). MHC-1 (IIx), -2 (IIa), -4 (IIb), and -7 (slow/I) were identified based on the Mowse score (5118, 3951, 2526, and 2541 for MHC-1, -2, -4, and -7, respectively). However, more analysis is needed to confirm the expression of MHC-4 in bovine LT muscle because any query identified as a unique peptide of MHC-4 was not found. The queries that were identified as unique peptides could be used as peptide markers to confirm MHC-1 (14 queries), -2 (8 queries), and -7 (21 queries) in bovine LT muscle; no query identified as a unique peptide of MHC-4 was found. LC-MS/MS analysis is a useful approach to study MHC isoforms at the protein level.

• International Journal of Industrial Entomology and Biomaterials
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• v.17 no.1
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• pp.137-141
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• 2008

We previously isolated and cloned a cDNA of abaecin from the Bombus ignitus. In an effort to produce a large amount of soluble abaecin at low cost, we successfully expressed the peptide in Escherichia coli that are highly sensitive to its mature form. For this, we fused the peptide encoding 39 amino acids of mature B. ignitus abaecin to the thioredoxin gene together with a C-terminal 6xHis tag. An enterokinase cleavage site was introduced between the 6xHis tag and mature abaecin to allow final release of the recombinant peptide. A high yield of 9.6 mg soluble fusion protein from 200 ml of bacterial culture was purified by $Ni^{2+}$-charged His-Bind resin affinity column, and 1.4 mg of pure active recombinant abaecin was readily obtained by enterokinase cleavage, followed by affinity chromatograph. The molecular mass of recombinant abaecin peptide was determined by Tricin-SDS-PAGE analysis. The recombinant abaecin exhibited antibacterial activity against Gram-negative bacteria.

• Preventive Nutrition and Food Science
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• v.4 no.1
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• pp.28-32
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• 1999

A novel antimicrbial peptide , named HFS-I, was isolated and characterized from the skin of the hagfish, Eptatretus bugeri. The decapeptide with a molecular mass of 1279.5 Da was purified to homogeneity using a gel-filtration column, ion-exchange and C18 reverse-phase high performance liquid chromatograpy . The complete amino acid sequence of HFS-I, which was determined by a combination of an automated amino acid sequencing and FAB-MS, was F-P-W-W-L-S-G-K-Y-P-NH2. Comparison of the amino acid sequence with those of other known antimicrobial peptides revealed that HFS-I was a novel antimicrobial peptide. HFS-I showed a weak antimicrobial activity in vitro aganinst a broad spectrum of microorganism without hemolytic acitivity.

• Mycobiology
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• v.41 no.3
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• pp.149-154
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• 2013

An ${\alpha}$-glucosidase inhibitor was developed from Aspergillus oryzae N159-1, which was screened from traditional fermented Korean foods. The intracellular concentration of the inhibitor reached its highest level when the fungus was cultured in tryptic soy broth medium at $27^{\circ}C$ for five days. The inhibitor was purified using a series of purification steps involving ultrafiltration, Sephadex G-25 gel permeation chromatography, strong cation exchange solid phase extraction, reverse-phase high performance liquid chromatography, and size exclusion chromatography. The final yield of the purification was 1.9%. Results of the liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis indicated that the purified ${\alpha}$-glucosidase inhibitor was a tri-peptide, Pro-Phe-Pro, with the molecular weight of 360.1 Da. The IC50 value of the peptide against ${\alpha}$-glucosidase activity was 3.1 mg/mL. Using Lineweaver-Burk plot analysis, the inhibition pattern indicated that the inhibitor acts as a mixed type inhibitor.

• Bioinformatics and Biosystems
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• v.1 no.2
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• pp.109-114
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• 2006

In proteomics research, proteins are digested into peptides by an enzyme and in mass spectrometer, these peptides break into fragment ions to generate tandem mass spectra. The tandem mass spectral data obtained from the mass spectrometer consists of the molecular weights of the precursor ion and fragment ions. The precursor ion mass of tandem mass spectrum is the first value that is fetched to sort the candidate peptides in the database search. We look far the peptide sequences whose molecular weight matches with precursor ion mass of the mass spectrum. Then, we choose one peptide sequence that shows the best match with fragment ions information. The precursor ion mass of the tandem mass spectrum is compared with that of the digested peptides of protein database within the mass tolerance that is assigned by users according to the mass spectrometer accuracy. In this study, we used reversed sequence database method to analyze the molecular weight distribution of precursor ions of the tandem mass spectra obtained by the FT LTQ mass spectrometer for human plasma sample. By reinterpreting the precursor ion mass distribution, we could compute the experimental accuracy and we suggested a method to improve the protein identification performance.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.700-707
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• 2010

A novel antioxidative peptide (APVPH I, antioxidative peptides from venison protein hydrolysates I) was purified from venison by enzymatic hydrolysis, column chromatography of DEAE-Sephacel, and high-performance liquid chromatography. The molecular mass of the purified peptide was found to be 9,853 Da and the amino acid sequences of the purified peptide was Met-Gln-Ile-Phe-Val-Lys-Thr-Leu-Thr-Gly. The purpose of this study was to evaluate the effects of APVPH I against $H_2O_2$-induced neuronal cells damage in PC-12 cells. Antioxidative enzyme levels in cultured neuronal cells were increased in the presence of the peptide. In addition, APVPH I inhibited productions of nitric oxide (NO), reactive oxygen species (ROS), malondialdehyde (MDA), and cell death against $H_2O_2$-induced neuronal cell damage in PC-12 cells. It was presumed to be APVPH I involved in regulating the apoptosis-related gene expression in the cell environment. The present results indicate that APVPH I substantially contributes to antioxidative properties in neuronal cells.