• Food Science and Biotechnology
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• v.14 no.5
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• pp.581-585
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• 2005

The antimicrobial activity of partially purified enterocin K25, produced by Enterococcus sp. K25, was abolished by proteases such as pepsin and proteinase K. The bacteriocin was resistant to heat treatment at $75^{\circ}C$ for 15 min and lost 75% of its activity at $100^{\circ}C$ for 30 min. Enterocin K25 showed bactericidal mode of action against an indicator strain, Lactobacillus plantarum NCDO 955. Enterocin K25 was purified to 112.6-fold purity via conventional steps of ammonium sulfate precipitation, ion exchange chromatography, and reversed phase high performance liquid chromatography (RP-HPLC). The molecular mass of the purified enterocin K25 was estimated as 4.3 kDa on an electrophoresis gel. Plasmid (${\sim}6.5\;kb$) linkage of production of enterocin K25 was confirmed by plasmid curing.

• 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.

• Korean Journal of Pharmacognosy
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• v.35 no.3 s.138
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• pp.179-183
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• 2004

Psoralen is used in the treatment of vitiligo and angelicin(isopsoralen) is a photosensitizing agent. A reversed-phase high performance chromatographic method was developed to determine the contents of psoralen and angelicin from Psoraleae Semen and processed Psoraleae Semen. The contents of psoralen and angelicin from Psoraleae Semen showed 0.39% and 0.34% respectively. Processing Psoraleae Semen showed that increased the contents of psoralen (0.52%) and angelicin (0.50%).

• Ocean and Polar Research
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• v.42 no.1
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• pp.15-20
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• 2020

The marine sponge Hyrtios sp. collected in the Philippines was extracted and partitioned. The resulting organic layer was purified by C₁₈ reversed-phase column chromatography and HPLC to achieve the separation of nine scalarane-type sesterterpenes, including one new compound with eight known scalarane analogs. The chemical structures of the isolated compounds 1-9 were elucidated by 1D and 2D NMR and MS data analysis. All nine compounds were evaluated for their antibacterial activities against three Gram-positive and three Gram-negative bacteria. The compound 3 exhibited potent antibacterial activities against Bacillus subtilis and Micrococcus luteus. The compounds 7 and 9 displayed considerable activities against Bacillus subtilis and the others had moderate results.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2003.04a
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• pp.76-76
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• 2003

Here we report an antifungal peptide isolation from G. mellonella larvae. The peptide shows a high degree of sequence homology to an insect defensin, named heliomicin, first reported in Lepidoptera. The peptide was purified by a three-step procedure consisting of acid extraction, gel permeation chromatography and reversed-phase HPLC. First the N-terminal amino acid sequence of the purified peptide was determined by automated Edman degradation. (omitted)

• Preventive Nutrition and Food Science
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• v.6 no.4
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• pp.244-246
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• 2001

Angiotensin converting enzyme (ACE) inhibitor acts on the inhibition of ACE and causes a decrease in blood pressure. There have been several reports on screening of ACE inhibitors from natural food products and protein hydrolysates of various food sources. Ripe Cucurbita moschata Duch has been used as an oriental medicine in Korea. To isolate ACE inhibitors, crude water extracts of the edible portion of ripe Cucurbita moschata Duch were obtained after heating in water at 95$^{\circ}C$ for 2 h. Crude extracts were then filtered using PM-10 and YM-1 membranes. The membrane-filtered solution was loaded onto Sephadex G-15 column equlibrated with a phosphate buffer. Among the four major fractions of gel permeation chromatography, the second fraction had the highest inhibitory activity of 65%. Further purification of the fraction using reversed-phase HPLC with a $C_{18}$ column produced ACE inhibitors, which were identified as a mixture having molecular mass of 222 and 273 by Tandem mass spectrometry.

• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.52-55
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• 1993

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[Ap(S)A] was performed by the condensation of protected deoxyadenosine, 2,5-dichlorophenylphosphorodichloridothioate and 1-hydroxybenzotriazole in THF. Their designation of configuration at phosphorus as $R_p\;and\;S_p$ follows from analysis of $^{31}P$-NMR spectroscopy and reversed-phase HPLC and the stereospecificity in the hydrolysis catalyzed by nuclease Pl.

• Bulletin of the Korean Chemical Society
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• v.18 no.4
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• pp.428-432
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• 1997

The dephosphorylation specificity of protein phosphatase 2A (PP2A), calcineurin (PP2B) and protein phosphatase 2C (PP2C) were studied in vitro using myelin basic protein (MBP) as a model substrate which was fully phosphorylated at multiple sites by protein kinase C (PKC) or cyclic AMP-dependent protein kinase (PKA). In order to determine the site specificity of phosphates in myelin basic protein, the protein was digested with trypsin and the radioactive phosphopeptide fragments were isolated by high performance liquid chromatography (HPLC) on reversed-phase column. Subsequent analysis and/or sequential manual Edman degradation of the purified phosphopeptides revealed that Thr-65 and Ser-115 were most extensively phophorylated by PKA and Ser-55 by PKC. For the dephosphorylation kinetics, the phosphorylated MBP was treated with calcineurin or PP2C with various time intervals and the reaction was terminated by direct tryptic digest. Both Thr-65 and Ser-115 residues were dephosphorylated more rapidly than any other ones by phosphatases. However it can be differentiated further by first-order kinetics that the PP2B dephosphorylated both Thr-65 and Ser-115 with almost same manner, whereas PP2C dephosphorylated somewhat preferentially the Ser-115.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.194.1-194.1
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• 2003

Ternstroemia japonica (Theaceae) is widely distributed in Korea, Japan, Taiwan and China. The tree is a useful source of lumber, dye and horticulture. Its fruits have been used as folk medicine in Japan for the treatment of chest pain or numbness. Previously, we have isolated saponins and jacaranone derivatives from the fruits. In our continuous study on the same plant, the leaves of Ternstroemia japonica were extracted with MeOH and the MeOH extract was fractionated with solvents. The n-BuOH soluble fraction was separated by repeated column chromatographies on silica gel and Sephadex LH-20, and further purified by reversed phase HPLC. (omitted)

• Journal of Environmental Science International
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• v.33 no.3
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• pp.205-215
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• 2024

Antibiotics are substances produced by microorganisms that kill or inhibit and are essential for infectious diseases management. This study aimed to provide basic data for overcoming antibiotic resistance in the marine bacterium LJ-18. The API 20NE and API 50CH kits were used to identify this microorganism. Morphological, physiological, and biochemical properties were investigated using MacFaddin's manuals. Subsequently, isolated LJ-18 was found to belong to a genus of Streptomyces that forms mycelia. LJ-18 also grew well at 28-32℃ on modified Bennett's agar. To isolate and purify the antibacterial compound, LJ-18 culture was divided into ethyl acetate and distilled water fractions. Considerable antimicrobial activity against various pathogenic microorganisms, including methicillin-resistant Staphylococcus aureus (MRSA), was confirmed in the C₁₈ ODS open column fractions. Peak 2 compound was obtained using reversed-phase HPLC. As a result, this compound had a significant antimicrobial activity against various pathogenic microorganisms. In particular, it showed strong activity against MRSA, Mycobacterium smegmatis, Bacillus subtilis, Bacillus cereus, and Staphylococcus aureus.