• Mass Spectrometry Letters
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• v.3 no.2
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• pp.47-49
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• 2012

Myoglobin was hydrolyzed by microwave-assisted weak acid hydrolysis with 2% formic acid at $37^{\circ}C$, $50^{\circ}C$, and $100^{\circ}C$ for 1 h. The most effective hydrolysis was observed at $100^{\circ}C$. Hydrolysis products were investigated using matrixassisted laser desorption/ionization time-of-flight mass spectrometry. Most cleavages predominantly occurred at the C-termini of aspartyl residues. For comparison, weak acid hydrolysis was also performed in boiling water for 20, 40, 60, and 120 min. A 60- min weak acid hydrolysis in boiling water yielded similar results as a 60-min microwave-assisted weak acid hydrolysis at $100^{\circ}C$. These results strongly suggest that microwave irradiation has no notable enhancement effect on acid hydrolysis of proteins and that temperature is the major factor that determines the effectiveness of weak acid hydrolysis.

• Mass Spectrometry Letters
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• v.14 no.2
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• pp.48-55
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• 2023

This study compares the efficiency of weak acid hydrolysis (WAH) using formic acid (FA) and hydrochloric acid (HCl) in the analysis of myoglobin peptides. WAH using 2% and 5% formic acid resulted in the identification of 32 peptides, with varying degrees of cleavage at the C-terminus of aspartic acid residues. HCl WAH with different concentrations demonstrated an increase in the total number of identified peptides but a decrease in fully cleaved peptides as the HCl concentration increased. Notably, deamidation was observed during HCl WAH but not in FA WAH. The addition of HCl WAH after FA WAH provided a similar pattern to HCl WAH, with slightly higher levels of hydrolysis. These findings highlight distinct cleavage patterns and deamidation effects between FA and HCl in the context of WAH.

• Mass Spectrometry Letters
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• v.9 no.2
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• pp.46-50
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• 2018

The effects of temperature and acetonitrile (ACN) concentration on microwave-assisted weak-acid hydrolysis of proteins were investigated. Myoglobin was hydrolyzed for 1 h using 2% formic acid and a microwave with different concentrations of ACN (0, 5, and 10%) at various temperatures (50, 60, 70, 80, 90, and $100^{\circ}C$). The numbers of peptides identified with each concentration of ACN were the same for each temperature. The greatest number of peptides (18 total) was obtained with hydrolysis at $100^{\circ}C$, and 6 of these were a result of additional removal of aspartic acid at the C-terminus. Hydrolysis at $80^{\circ}C$ resulted in 13 peptides, of which only 1 was generated by the additional removal of aspartic acid, and 12 were observed with hydrolysis at $100^{\circ}C$. Our results demonstrate that microwave-assisted weak-acid hydrolysis of proteins can be performed successfully at $80^{\circ}C$, which could be beneficial for limiting side reactions and generating larger peptide sequences.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.6
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• pp.1110-1116
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• 1998

To determine the optimum conditions for the enzymic hydrolysis against wheat gluten of high con centrations (6~14%, w/w, protein), a hydrolysis system combining weak acid pretreatment and enzymic hydrolysis was investigated. Alcalase showed the highest DH(degree of hydrolysis) of the tested proteases. After hydrolysis by alcalase, subsequently peptidases were applied for the better DH of the wheat gluten hydrolyzate. Peptidase NP2 showed the highest DH of the tested peptidases, but flavour zyme was shown for the lowest bitter taste of the resulting hydrolyzate. In order to minimize aggregation or gelling at higher initial substrate concentration during heat treatment, wheat gluten suspension was pretreated with possibly low concentrations of hydrochloric acid at 105oC for 1 hour, and then enzy matically hydrolysed with alcalase and subsequently with flavourzyme. Each required minimum concen tration of hydrochloric acid in the wheat gluten suspension of 6, 8, 10, 12, and 14%(w/w, protein) was 0.10, 0.15, 0.20, 0.225, and 0.275N, respectively. After the subsequent enzymic treatment by alcalase and peptidase NP2 for 24 hrs, the nitrogen solubility in the final wheat gluten hydrolysates was increased to 94.9, 86.4, 85.3, 89.3 and 95.0%, and their amino nitrogen content was increased to 2.87, 5.68, 7.34, 9.71 and 12.50mg/m, respectively.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.27-28
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• 2013

• Mass Spectrometry Letters
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• v.10 no.3
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• pp.79-83
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• 2019

Horse heart myoglobin (MYG) and bovine serum albumin (BSA) were hydrolyzed by microwave-assisted weak-acid hydrolysis for 10, 20, 30, 40, 50, and 60 min using 2% formic acid (FA) at $100^{\circ}C$. Generally, the number of identified peptides increased with increasing irradiation time, indicating that the duration of microwave irradiation is linked to the efficiency of hydrolysis. For MYG, irradiation for 60 min provided the highest number of identified peptides, the greatest sequence coverage values and the highest MASCOT score values among the investigated irradiation times. Irradiation of BSA for 50 min, however, yielded a greater number of peptides than irradiation for 60 min due to the generation of miscleaved peptides after microwave irradiation for 50 min.

• Journal of Sericultural and Entomological Science
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• v.42 no.2
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• pp.104-108
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• 2000

To hydrolyze insolule sericin the enzyme hydrolysis was used, and then obtained the results as given belows. When insoluble sericin was hydrolyzed by enzyme treatment, the solubility was best at pH 7, 60$\^{C}$ and was slightly increased both above 2 hours treatment and above 10% of enzyme concentration. As the results of electrophoresis, the distribution of molecular weight of sericin powder obtained by enzyme hydrolysis was very weak and showed in the wide range having no distinguishable band. Average degree of polymerzations (A.D.P.) of sericin hydrolyzed by enzyme were about 4.1∼6.3, average molecular weight were about 470∼730. The whiteness of the sericin powder obtained by enzyme hydrolysis was high and increased slightly with higher treatment concentration of enzyme. As the results of amino acid analysis, the amino acid analysis, the amino acid composition of the sericin powder from the enzyme treatment were similar to which located at near 230$\^{C}$ and 320$\^{C}$. The peak of near 230$\^{C}$ could not been found in the sericin powder obtained by enzyme hydrolysis.

• Journal of Integrative Natural Science
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• v.8 no.1
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• pp.48-55
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• 2015

Novel 2'(${\beta}$)-methyl-5'-deoxyapiose purine phosphonic acid analogues were designed and synthesized from 2-propanone-1,3-diacetate. Condensation successfully proceeded from a glycosyl donor 9 under Vorbr${\ddot{u}}$ggen conditions. Condensation of aldehyde 14 with Wittig reagent [(diethoxyphosphinyl)methylidene] triphenylphosphorane gave the desired nucleoside phosphonate analogues 15. Ammonolysis and hydrolysis of phosphonates gave the nucleoside phosphonic acid analogue 17 and 19. The synthesized nucleoside analogues were subjected to antiviral screening against HIV-1. The adenine analogue 19 exhibited weak in vitro activities against HIV-1.

• Composites Research
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• v.31 no.6
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• pp.371-378
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• 2018

In this study, the thermoelastic properties of poly lactic acid (PLA) based nanocomposites are predicted by molecular dynamics (MD) simulation and a micromechanics model. The stereocomplex mixed with L-lactic acid (PLLA) and D-lactic acid (PDLA) is modeled as matrix phase and a single walled carbon nanotube is embedded as reinforcement. The glass transition temperature, elastic moduli and thermal expansion coefficients of pure matrix and nanocomposites unit cells are predicted though ensemble simulations according to the hydrolysis. In micromechanics model, the double inclusion (D-I) model with a perfect interface condition is adopted to predict the properties of nanocomposites at the same composition. It is found that the stereocomplex nanocomposites show prominent improvement in thermal stability and interfacial adsorption regardless of the hydrolysis. Moreover, it is confirmed from the comparison of MD simulation results with those from the D-I model that the interface between CNT and the stereocomplex matrix is slightly weak in nature.

• Journal of Life Science
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• v.26 no.8
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• pp.976-982
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• 2016

Seaweed has high growth rate, low land usage, high CO₂ absorption and no competition for food resources. Therefore, the use of lignin-free seaweed as a raw material is arising as a third generation biomass for bioethanol production. Various pretreatment techniques have been introduced to enhance the overall hydrolysis yield, and can be categorized into physical, chemical, biological, enzymatic or a combination. Thermal acid hydrolysis pretreatment is one of the most popular methods to attain high sugar yields from seaweed biomass for economic reasons. At thermal acid hydrolysis conditions, the 3,6-anhydro-galactose (AHG) from biomass could be converted to 5-hydroxymethylfurfural (HMF), which might inhibit the cell growth and decrease ethanol production. AHG is prone to decomposition into HMF, due to its acid-labile character, and subsequently into weak acids such as levulinic acid and formic acid. These inhibitors can retard yeast growth and reduce ethanol productivity during fermentation. Thus, the carbohydrates in seaweed require effective treatment methods to obtain a high concentration of monosaccharides and a low concentration of inhibitor HMF for ethanol fermentation. The efficiency of bioethanol production from the seaweed biomass hydrolysate is assessed by separate hydrolysis and fermentation (SHF). To improve the efficiency of the ethanol fermentation of mixed monosaccharides, the adaptation of yeast to high concentration of sugar could make simultaneous utilization of mixed monosaccharides for the production of ethanol from seaweed.