• Title, Summary, Keyword: protein modification

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Surface modification of polymeric membranes for low protein binding

  • Higuchi, Akon;Tamai, Miho;Tagawa, Yoh-Ichi;Chang, Yung;Ling, Qing-Dong
    • Membrane Water Treatment
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    • v.1 no.2
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    • pp.103-120
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    • 2010
  • Surface modification of microfiltration and ultrafiltration membranes has been widely used to improve the protein adsorption resistance and permeation properties of hydrophobic membranes. Several surface modification methods for converting conventional membranes into low-protein-binding membranes are reviewed. They are categorized as either physical modification or chemical modification of the membrane surface. Physical modification of the membrane surface can be achieved by coating it with hydrophilic polymers, hydrophilic-hydrophobic copolymers, surfactants or proteins. Another method of physical modification is plasma treatment with gases. A hydrophilic membrane surface can be also generated during phase-inverted micro-separation during membrane formation, by blending hydrophilic or hydrophilic-hydrophobic polymers with a hydrophobic base membrane polymer. The most widely used method of chemical modification is surface grafting of a hydrophilic polymer by UV polymerization because it is the easiest method; the membranes are dipped into monomers with and without photo-initiators, then irradiated with UV. Plasma-induced polymerization of hydrophilic monomers on the surface is another popular method, and surface chemical reactions have also been developed by several researchers. Several important examples of physical and chemical modifications of membrane surfaces for low-protein-binding are summarized in this article.

Inhibitory effects of dl-Puerol A in the root of Sophora japonica on copper ion-induced protein oxidative modification of mouse brain homogenate in vitro

  • Toda, Shizuo;Shirataki, Yoshiaki
    • Oriental Pharmacy and Experimental Medicine
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    • v.4 no.3
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    • pp.211-214
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    • 2004
  • The inhibitory effect of dl-puerol A as but-2-enolide isolated from Sophora japonica was investigated on copper ion-induced protein oxidative modification in vitro. It inhibited copper-induced protein oxidative modification. However, its inhibitory effect was a little weaker than that of $dl-{\alpha}-tocopherol$ as an antioxidant. The results demonstrated that dl-puerol A, one of but-2-enolides, might be of use in the oxidative stress.

Biophysical effect of lipid modification at palmitoylation site on the structure of Caveolin 3

  • Ma, Yu-Bin;Kang, Dong-Hoon;Kim, Myeongkyu;Kim, Ji-Hun
    • Journal of the Korean Magnetic Resonance Society
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    • v.23 no.3
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    • pp.67-72
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    • 2019
  • Caveolae are small plasma membrane invaginations that play many roles in signal transduction, endocytosis, mechanoprotection, lipid metabolism. The most important protein in caveolae is the integral membrane protein, caveolin, which is divided into three families such as caveolin 1, caveolin 2, and caveolin 3. Caveolin 1 and 3 are known to incorporate palmitate through linkage to three cysteine residues. Regulation of the protein palmitoylation cycle is important for the cellular processes such as intracellular localization of the target protein, membrane association, conformation, protein-protein interaction, and activity. However, the detailed aspect of individual palmitoylation has not been studied. In the present work, the role of each lipid modification at three cysteines was studied by NMR. Our results suggest that each lipid modification at the natively palmitoylation site has its own roles. For example, lipidations to C106 and C129 are play a role in structural stabilization, however, interestingly, lipid modification to C116 interrupts the structural stabilization.

The Physicochemical Properties of Modified Soybean Protein Isolate by Dimethylglutarylation (Dimethylglutarylation에 의한 변형대두단백질의 물리화학적 특성)

  • Choi, One-Kyun;Jung, Chul-Won
    • Journal of the Korean Society of Food Culture
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    • v.14 no.5
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    • pp.467-476
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    • 1999
  • We studied to improve the functional properties of soybean protein isolate by dimethylglutarylation and acetylation. Soybean protein isolate was acylated rapidly up to 80% modification and more of 80% modification was proceed slowly. Electrophoretic analysis showed that more changes in modified protein. Also, modification of soybean protein produced more ionizable tyrosines and exposed more hydrophobic groups, while modified protein exhibited a loss of reactive sulfhydryl groups. Spectrophoretic studies demonstrated that the shift was occurred at the UV 278nm and fluorescence 333nm, respectively, and the intensity decreased as the degree of modification was increased.

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Effects of ${\alpha}$-Chymotrypsin Modification on the Functional Properties of Soy Protein Isolates

  • Ahn Tae-Hyun;Lee Sook-Young
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.51 no.2
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    • pp.148-153
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    • 2006
  • Effects of ${\alpha}$-chymotrypsin modification on degree of hydrolysis (DH), solubility, emulsifying capacity and thermal aggregation of laboratory-purified soy protein isolate (SPI) using a lipoxygenase-defected soybean (Jinpum-kong) and commercial soy protein isolate (Supro 500E) were compared. SPIs were hydrolyzed by ${\alpha}$-chymotrypsin at pH 7.8 and $37^{\circ}C$ for 30 min. DHs of Supro 500E and Jinpum-kong SPI were increased by ${\alpha}$-chymotrypsin modification, and DH of Supro 500E was higher than that of Jinpum-kong SPI. DH of ${\alpha}$-chymotrypsin treated Jinpum-kong SPI was similar with untreated Supro 500E and DH of treated Supro 500E was the highest. Solubility, emulsifying capacity and thermal aggregation of SPIs were increased by ${\alpha}$-chymotrypsin modification, and these changes were highly related to changes in DH. Functional properties of Supro 500E were higher than Jinpum-kong SPI in both of untreated and ${\alpha}$-chymotrypsin treated SPIs.

Regulation of post-translational modification in breast cancer treatment

  • Heo, Kyung-Sun
    • BMB Reports
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    • v.52 no.2
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    • pp.113-118
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    • 2019
  • The small ubiquitin-related modification molecule (SUMO), one of the post-translational modification molecules, is involved in a variety of cellular functions where it regulates protein activity and stability, transcription, and cell cycling. Modulation of protein SUMOylation or deSUMOylation modification has been associated with regulation of carcinogenesis in breast cancer. In the dynamic processes of SUMOylation and deSUMOylation in a variety of cancers, SUMO proteases (SENPs), reverse SUMOylation by isopeptidase activity and SENPs are mostly elevated, and are related to poor patient prognosis. Although underlying mechanisms have been suggested for how SENPs participate in breast cancer tumorigenesis, such as through regulation of target protein transactivation, cancer cell survival, cell cycle, or other post-translational modification-related machinery recruitment, the effect of SENP isoform-specific inhibitors on the progression of breast cancer have not been well evaluated. This review will introduce the functions of SENP1 and SENP2 and the underlying signaling pathways in breast cancer for use in discovery of new biomarkers for diagnosis or therapeutic targets for treatment.

Modification of Turnip yellow mosaic virus coat protein and its effect on virion assembly

  • Shin, Hyun-Il;Chae, Kwang-Hee;Cho, Tae-Ju
    • BMB Reports
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    • v.46 no.10
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    • pp.495-500
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    • 2013
  • Turnip yellow mosaic virus (TYMV) is a positive strand RNA virus. We have modified TYMV coat protein (CP) by inserting a c-Myc epitope peptide at the N- or C-terminus of the CP, and have examined its effect on assembly. We introduced the recombinant CP constructs into Nicotiana benthamiana leaves by agroinfiltration. Examination of the leaf extracts by agarose gel electrophoresis and Western blot analysis showed that the CP modified at the N-terminus produced a band co-migrating with wild-type virions. With C-terminal modification, however, the detected bands moved faster than the wild-type virions. To further examine the effect, TYMV constructs producing the modified CPs were prepared. With N-terminal modification, viral RNAs were protected from RNase A. In contrast, the viral RNAs were not protected with C-terminal modification. Overall, the results suggest that virion assembly and RNA packaging occur properly when the N-terminus of CP is modified, but not when the C-terminus is modified.

Functional Properties of Modified Soybean Protein Isolate by Dimethylglutarylation (Dimethylglutarylation에 의한 변형대두단백질의 기능적 특성)

  • Choi, One-Kyun;Jung, Chul-Won
    • Journal of the Korean Society of Food Culture
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    • v.14 no.5
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    • pp.477-485
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    • 1999
  • This study was conducted to improve the functional properties of soybean protein isolate by dimethylglutarylation and acetylation. Amino acid composition and solubility of modified soybean protein by dimethylglutarylation were not changed, but lysine and trypsin inhibitor activity was decreased an isoelectric point was moved from pH5 to pH4 as a result of modification. Emulsification capacity and stability, foaming capacity and thermal stability were increased by the modification. In that 91% dimethylglutarylated protein did not coagulate when heating at $100^{\circ}C$ for 20 min. while its foaming stability was decreased. Whereas specific gravity was decreased by the modification of the soybean protein, relative viscosity and whiteness were improved. Generally, dimethylglutarylation produced more conformational changes in protein system than did in acetylation.

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Comparative Studies of Protein Modification Mediated by Fenton-like Reactions of Iron, Hematin, and Hemoglobin: Generation of Different Reactive Oxidizing Species

  • Kim, Young-Myeong;Kim, Sung-Soo;Kang, Gu;Yoo, Yeong-Min;Kim, Ki-Mo;Lee, Mi-Eun;Han, Jeong-A;Hong, Sun-Joo
    • BMB Reports
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    • v.31 no.2
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    • pp.161-169
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    • 1998
  • TThe reactive oxygen species oxidatively modify the biological macromolecules, including proteins, lipids, and nucleic acids. Iron- and heme-mediated Fenton-like reactions produce different pro-oxidants. However, these reactive products have not been clearly characterized. We examined the nature of the oxidizing species from the different iron sources by measuring oxidative protein modification and spectroscopic study. Hemoglobin (Hb) and methemoglobin (metHb) were oxidatively modified in $O{\array-\\\dot{2}}$ and $H_{2}O_{2}$ generating systems. Globin and bovine serum albumin (BSA) were also modified by iron, iron-EDTA, hematin, and Hb in an $O{\array-\\\dot{2}}$ generating system. In a $H_{2}O_{2}$ generating system, the iron- and iron-EDTA-mediated protein modifications were markedly reduced while the Hb-and hematin-mediated modifications were slightly increased. In the $O{\array-\\\dot{2}}$ generating system, the iron- and iron-EDTA-mediated protein modifications were strongly inhibited by superoxide dismutase (SOD) or catalase, but heme- and Hb-mediated protein modifications were inhibited only by catalase and slightly increased by SOD. Mannitol, 5,5-dimethyl-l-pyrroline-N-oxide (DMPO), deoxyribose, and thiourea inhibited the iron-EDTA-mediated protein modification. Mannitol and DMPO, however, did not exhibit significant inhibition in the hematin-mediated modification. Desferrioxamine (DFO) inhibited protein modification mediated by iron, but cyanide and azide did not, while the hematin-mediated protein modification was inhibited by cyanide and azide, but not significantly by DFO. The protein-modified products by iron and heme were different. ESR and UV-visible spectroscopy detected the DMPO spin adduct of the hydroxyl radical and ferryl ion generated from iron-EDTA and metHb, respectively. These results led us to conclude that the main oxidizing species are hydroxyl radical in the iron-EDTA type and the ferry I ion in the hematin type, the latter being more effective for protein modification.

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Acetylation of Fist Protein form Alaska Pollack (명태 근육단백질의 아세틸화에 따른 기능성의 변화)

  • 홍정화;최진호;변대석
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.19 no.3
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    • pp.219-223
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    • 1990
  • Myofibrillar protein from Alaska pollack was modified with acetic anhydride at pH 7.5 and $25^{\circ}C$ and changes in functional properties as affected by the degree of modification were determined. Acetylation of myofibrillar protein resulted in protein with unique functional properties dependent upon the degree of acetylation. By selecting appropriate degree of modification it was possible to control protein solubility heat coagulability calcium precipitability foaming and emulsion capa-city.

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