• Fisheries and Aquatic Sciences
• /
• v.24 no.4
• /
• pp.163-170
• /
• 2021

Peptides are naturally occurring biological molecules that are found in all living organisms. These biologically active peptides play a key role in various biological processes. The aim of this study is the extraction and the purification of bioactive materials that induce relaxation of an apical muscle from the pyloric caeca of Patiria pectinifera. The acidified pyloric caeca extract was partially separated by the solid phase extraction using a stepwise gradient on Sep-Pak C18 cartridge. Among the fractions, materials eluted with 60% methanol/0.1% trifluoroacetic acid was put a thorough of a series of high performance liquid chromatography (HPLC) steps to isolate a neuropeptide with relaxation activity. The purified compound was eluted at 28% acetonitrile in 0.1% trifluoroacetic acid with retention time of 25.8 min on the CAPCELL-PAK C18 reversed-phase column. To determine the molecular weight and the amino acid sequence of the purified peptide, LC-MS and Edman degradation method were used, respectively. The primary structure of the peptide was determined to be FGMGGAYDPLSAGFTD which corresponded to the amino acid sequence of a starfish myorelaxant peptide (SMP) isotype (SMPb) found in the cDNA sequence encoding SMPa and its isotypes. In this study, a muscle relaxant neuropeptide (SMPb) has been isolated from pyloric caeca of starfish P. pectinifera. This is the first report of SMPb isolation on the protein level from P. pectinifera.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.9
• /
• pp.1593-1601
• /
• 2017

Vibrio species are generally recognized as pathogens predominant in seafood along coastal areas. The food industry has sought to develop efficient microbial detection methods. Owing to the limits of conventional methods, this study aimed to establish a rapid identification method for Vibrio isolated from Korea, based on matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Four different preparation procedures were compared to determine the appropriate means to pretreat Vibrio species, using 17 isolates and five reference strains. Extended direct transfer and full formic acid extraction methods using bacterial colonies on agar plates revealed very low identification rates. Formic acid and trifluoroacetic acid (TFA) extractions using bacterial broth cultures were also performed. All Vibrio isolates and reference strains prepared by TFA extraction were successfully identified to the species level (17/22, 77.3%) and to the genus level (5/22, 22.7%). Thus, TFA extraction was considered the most appropriate method to pretreat Vibrio species for MALDI-TOF MS. The remaining 33 isolates and two reference strains were prepared by TFA extraction and analyzed by MALDI-TOF MS. Overall, 50 isolates were identified to the species level (40/50, 80%) and to the genus level (10/50, 20%). All isolates were identified as 43 V. alginolyticus, six V. parahaemolyticus, and one V. vulnificus species. V. alginolyticus and V. parahaemolyticus were isolated from fish offal (87.5% and 12.5%, respectively), seawater (91.3%, 8.7%), and shellfish (62.5%, 37.5%), whereas V. alginolyticus and V. vulnificus were isolated from sediment (90.9% and 9.1%, respectively). This study established a reliable system of MALDI-TOF MS preparation and analysis for Vibrio identification.

• Bulletin of the Korean Chemical Society
• /
• v.27 no.6
• /
• pp.903-908
• /
• 2006

Various extraction procedures were investigated using reference materials and samples to evaluate extraction efficiency and effectiveness. Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure total arsenic and to quantitate arsenic species when coupled to an HPLC (high pressure liquid chromatography). Arsenic species were extracted from rice flour (NIST SRM 1568a) with water/methanol mixtures using accelerated solvent extraction (ASE). Total arsenic extraction efficiency ranged from 42 to 64%, for water and various methanol concentrations. From spinach (NIST SRM 1570), freeze-dried apple, and rice flour (NIST SRM 1568a), arsenic species were extracted with trifluoroacetic acid (TFA) at 100 ${^{\circ}C}$. Total arsenic extraction efficiency was 90% for spinach, 75% for freeze-dried apple, and 83% for rice flour. Enzymatic extraction with alpha-amylase and sonication resulted in extraction efficiency of 104% for rice flour, 98% for freeze-dried apple, and 7% for spinach. Chromatograms of arsenic species extracted by the optimum extraction methods were obtained, and the species were quantified. Arsenite (As(III)), arsenate (As(V)), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) were found in the apple sample, and DMA and As(V) in the rice flour sample. As(V) and MMA were found in three herbal dietary supplement samples.

• Analytical Science and Technology
• /
• v.37 no.4
• /
• pp.211-219
• /
• 2024

This study presents a sensitive and reliable method for determining tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC) residues in shrimp samples. A two-step process involving liquid-liquid extraction (LLE) followed by solid-phase extraction (SPE) was developed prior to HPLC analysis. The target analytes were effectively extracted using EDTA/McIlvaine buffer (pH 4.0): methanol (80:20, %v/v), with subsequent clean-up using a C18 SPE cartridge. HPLC separation was conducted on a C18 column (250 mm × 4.6 mm i.d., 5 ㎛) at 30 ℃, using 0.01 % trifluoroacetic acid (A) and acetonitrile (B) as the mobile phase. A gradient elution protocol was applied, transitioning from 85(A):15(B) %v/v to 70(A):30(B) %v/v at 7 min, with a 5 min hold, followed by adjustment to 85(A):15(B) %v/v for 13-14 min. The detection was performed using photodiode array (PDA) at 365 nm with a flow rate of 1.0 mL/min. The calibration curves exhibited good linearity within a concentration range of 0.4-6.0 ㎍/mL (R² > 0.995). The limits of detection (LOD) for TC, OTC, and CTC in shrimp were 0.034, 0.029, and 0.021 ㎍/mL, respectively. The limits of quantitation (LOQ) for TC, OTC, and CTC were found to be 0.114, 0.097, and 0.071 ㎍/mL, respectively. Recoveries of TC, OTC, and CTC from spiked shrimp samples ranged from 91.0 % to 95.5 %, 92.4 % to 97.2 %, and 93.3 % to 96.6 %, respectively. This method was successfully applied to the determination of TC, OTC, and CTC residues in shrimp samples sourced from various local markets.

• Korean Journal of Environmental Agriculture
• /
• v.25 no.4
• /
• pp.359-364
• /
• 2006

Reversed-phase high-performance liquid chromatography (HPLC) techniques were developed to quantify abamectin (ABM) in paprika (Capsicum annum). Separation was achieved on a $C_{18}$ ODS column with a mobile phase of acetonitrile/water (96/4, v/v) mixture in an isocratic elution at the flow tate of 1.2 mL/min for avermectins (AVMs). The retention times were 8.0 and 9.7mins for AVM $B_{lb}$ and AVM $B_{1a}$, respectively. Residual AVMs (sum of AVM $B_{1a}$, AVM $B_{1b}$ and 8,9-Z-AVM $B_{1a}$) in the vegetable were extracted with acetonitrile, and the silica solid-phase extraction cartridges were used to purify the extract. AVMs were derivatized using trifluoroacetic acid and 1-methylimidazole, and the derivatives were determined with a fluorescence detector (excitation at 365 nm and emission at 470 nm). High and consistent recoveries, ranging from 93% to 115%, were obtained for AVM $B_{1a}$ and 8, 9-Z-AVM $B_{1a}$ at fortified levels of $20{\mu}g/kg\;and\;200{\mu}g/kg$ for paprika. The limit of quantitation (LOQ) was $2{\mu}g/kg$. The residual levels of AVMs in paprika in a field experiment from one day to seven days after the last application decreased from 18.40 to $7.59{\mu}g/kg$. The half-life $(T_{1/2})$ of AVMs in paprika was 1.47 days.

• Korean Journal of Food Science and Technology
• /
• v.20 no.5
• /
• pp.659-665
• /
• 1988

The ${\alpha}_{s1}$-and ${\beta}$-casein were purified by DEAE-cellulose chromatography and digested with alkaline protease from Bacillus subtilis. Bitter fractions from the hydrolyzates were isolated using n-butanol extraction, Sephadex G-25 gel chromatography, and high performance liquid chromatography. Peptide mixtures were separated by reverse-phase octadecyl silica column with linear gradient of 0-80% acetonitrile containing 0.1% trifluoroacetic acid. Major peaks were combined from replicate chromatographies and the bitterness of each peak was evaluated. The bitter-tasting peaks were rechromatograpied until isolated peaks were obtained. Three different bitter peptides(BP-I, BP-II, BP-III) were obtained from the ${\alpha}_{s1}$-casein hydrolyzate. BP-I was eluted at 34% acetonitrile and BP-II, 35%, BP-III, 26%, respectively. Two bitter peptides(BP-IV, BP-V) were isolated from the ${\beta}-casein$ hydrolyzate: BP-IV was eluted at 40% acetonitrile and BP-V, 42%. BP-V was the most hydrophobic peptide in the five bitter peptides. However, BP-I and BP-II tasted more bitter than BP-IV and BP-V.