• Macromolecular Research
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• v.11 no.1
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• pp.53-61
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• 2003

A molecular-thermodynamic model is developed for the salt-induced protein precipitation. The protein molecules interact through four intermolecular potentials. An equation of state is derived based on the statistical mechanical perturbation theory with the modified Chiew's equation for the fluid phase, Young's equation for the solid phase as the reference system and a perturbation based on the protein-protein effective two body potential. The equation of state provides an expression for the chemical potential of the protein. In a single protein system, the phase separation is represented by fluid-fluid equilibria. The precipitation behaviors are simulated with the partition coefficient at various salt concentrations and degree of pre-aggregation effect for the protein particles. In a binary protein system, we regard the system as a fluid-solid phase equilibrium. At equilibrium, we compute the reduced osmotic pressure-composition diagram in the diverse protein size difference and salt concentrations.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1756-1762
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• 2007

Envelope proteins of virus contain a segment of hydrophobic amino acids, called as fusion peptide, which triggers membrane fusion by insertion into membrane and perturbation of lipid bilayer structure. Potential fusion peptide sequences have been identified in the middle of L or M proteins or at the N-terminus of S protein in the envelope of human hepatitis B virus (HBV). Two 16-mer peptides representing the N-terminal fusion peptide of the S protein and the internal fusion peptide in L protein were synthesized, and their membrane disrupting activities were characterized. The internal fusion peptide in L protein showed higher activity of liposome leakage and hemolysis of human red blood cells than the N-terminal fusion peptide of S protein. Also, the membrane disrupting activity of the extracellular domain of L protein significantly increased when the internal fusion peptide region was exposed to N-terminus by the treatment of V8 protease. These results indicate that the internal fusion peptide region of L protein could activate membrane fusion when it is exposed by proteolysis.

• Biomolecules & Therapeutics
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• v.26 no.6
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• pp.533-538
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• 2018

Nitric oxide (NO) mediates various physiological and pathological processes, including cell proliferation, differentiation, and inflammation. Protein S-nitrosylation (SNO), a NO-mediated reversible protein modification, leads to changes in the activity and function of target proteins. Recent findings on protein-protein transnitrosylation reactions (transfer of an NO group from one protein to another) have unveiled the mechanism of NO modulation of specific signaling pathways. The intracellular level of S-nitrosoglutathione (GSNO), a major reactive NO species, is controlled by GSNO reductase (GSNOR), a major regulator of NO/SNO signaling. Increasing number of GSNOR-related studies have shown the important role that denitrosylation plays in cellular NO/SNO homeostasis and human pathophysiology. This review introduces recent evidence of GSNO-mediated NO/SNO signaling depending on GSNOR expression or activity. In addition, the applicability of GSNOR as a target for drug therapy will be discussed in this review.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2005.09a
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• pp.388-391
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• 2005

The Protein Structural and Functional Conservation need a common language for data definition. With the help of common language provided by Protein Ontology the high level of sequence and functional conservation can be extended to all organisms with the likelihood that proteins that carry out core biological processes will again be probable orthologues. The structural and functional conservation in these proteins presents both opportunities and challenges. The main opportunity lies in the possibility of automated transfer of protein data annotations from experimentally traceable model organisms to a less traceable organism based on protein sequence similarity. Such information can be used to improve human health or agriculture. The challenge lies in using a common language to transfer protein data annotations among different species of organisms. First step in achieving this huge challenge is producing a structured, precisely defined common vocabulary using Protein Ontology. The Protein Ontology described in this paper covers the sequence, structure and biological roles of Protein Complexes in any organism.

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.103-113
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• 2014

Hydrophobicity is the key concept to understand the role of water in protein folding, protein self-assembly, and protein-ligand interaction. Conventionally, hydrophobicity of amino acids in a protein has been argued based on hydrophobicity scales determined for individual free amino acids, assuming that those scales are unaltered when amino acids are embedded in a protein. Here, we investigate how the hydrophobicity of constituent amino acids depends on the protein context, in particular, on the total charge and secondary structures of a protein. To this end, we compute and analyze the hydration free energy - free energy change upon hydration quantifying the hydrophobicity - of three short proteins based on the integral-equation theory of liquids. We find that the hydration free energy of charged amino acids is significantly affected by the protein total charge and exhibits contrasting behavior depending on the protein net charge being positive or negative. We also observe that amino acids in the central ${\beta}$-strand sandwiched by ${\beta}$-sheets display more enhanced hydrophobicity than free amino acids, whereas those in the ${\alpha}$-helix do not clearly show such a tendency. Our results provide novel insights into the hydrophobicity of amino acids, and will be valuable for rationalizing and predicting the strength of water-mediated interaction involved in the biological activity of proteins.

• Plant Resources
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• v.8 no.2
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• pp.110-115
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• 2005

Ribosomal protein complex with ribosomal RNA to form the subunits of the ribosome serve essential functions in protein synthesis. A full-length cDNA (PRPS4) encoding ribosomal protein S4 has been isolated and its nucleotide sequence determined in ginseng plant (Panax ginseng). A PRPS4 cDNA is 1105 nucleotides long and has an open reading frame of 792 bp with a deduced amino acid sequence of 264 residues (pI 10.67). The deduced amino acid sequence of PRPS4 matched to the previously reported ribosomal protein S4 genes. Their degree of amino acid identity ranged from 68 to $92\%$. Phylogenetic analysis based on the amino acid residues showed that the PRPS4 grouped with ribosomal protein S4 of S. tuberosum (CAA54095).

• Journal of the East Asian Society of Dietary Life
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• v.5 no.3
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• pp.385-394
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• 1995

Our previous reports on the effect of dietary protein on methanethiol, ethacrynic acid, bromobenzene and carbon tetrachloride metabolism were overall reviewed. The methanethiol, ethacrynicacid and bromobenzene treated rats showed the more severe liver damage in those fed a low protein diet than those fed a standard protein diet. These xenobiotics treated rats showed the lower content of hepatic glutathione and its conjugated enzyme, glutathione S-transferase activities in those fed a low protein diet than those fed a standard protein diet. In case of carbon tetrachloride treated rats, the liver damage was more reduced in rats fed a low protein diet than those fed a standard protein diet. Concomitantly the hepatic cytochrome P-450 content, and its decreasing rate to the control were lower in rats fed a low protein diet than those fed a standard protein diet.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.1
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• pp.15-18
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• 1993

To evaluate an effect of dietary protein on the intoxication of methanethiol in rats, the methanethiol was intraperitoneally injected to the rats fed a low or high protein diet and then the liver weight per body weight and seurm levels of alanine aminotransferase (ALT) activities were determined to investigate the differences in liver damage between the animal groups fed low protein diet and that fed high protein diet. On the other hand, the hepatic glutathione content and its conjugating enzyme, glutathione S-transferase (GST) activity were determined to clarify the cause of difference in liver function between the two groups. The increasing rate of liver weigh/body wt., serum levels of ALT to its control group were higher in methanethiol-treated rats fed low protein diet than those fed high protein diet. The hepatic content of glutathione and GST activity were higher in rats fed high protein diet than those fed low protein diet and the decreasing rate of hepatic glu-tathione content to its control group was higher in rats fed low protein diet than those fed high protein diet. Furthermore, the hepatic GST activity in methanethiol-treated rats was higher in rats fed high protein diet than those fed low protein diet. In case of control group, the GST activity was also higher in rats fed high protein diet than those fed low protein diet.

• Journal of Nutrition and Health
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• v.32 no.8
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• pp.855-863
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• 1999

This study was performed to investigate the effect of dietary protein level throughout gestation and lactation on milk composition and on postnatal growth in infants, using rats as an animal model. Female Sprague-Dawley rats were provided with either high(25% ISP(Isolated Soy Protein)diet) or low protein diet(10% ISP diet) throughout gestation and lactation. Milk samples were taken for analysis from the lactating rats at days of 7, 14, 21, of lactation. Dams and some pups were killed after 4 weeks from parturtion (Experiment 1). Pups from dams of each diet groups were randomly selected and reared with 25% or 10% ISP diet for 4 more weeks (Experiment 2). In experiment 1, maternal protein intake and body weight gain throughout gestation and lactation was higher in 25% ISP group. Serum protein, Ca, Fe, Zn, K concentrations were significantly higher in 25% ISP group. There was no difference in birth weight between two groups, however the mean body weight at 4 weeks postpartum were significantly higher in 25% ISP group. Serum profiles of pups at weaning were similar to that of dams. Milk compositions were changed during lactation processes and were affected by dietary protein level. Lactose and Ca, Cu, Fe concentrations in milk were higher in 25% ISP group, whereas, lipid, triglyceride were higher in 10% ISP group. In experiment 2, food intake was higher in milk were higher in 25% ISP group but was unaffected by pup's dietary protein level after weaning. The weights of liver and kidney were affected by maternal protein intake. The weight of intestine was affected by pup's dietary protein level after weaning. The weight of femur and scapula were affected by maternal protein intake. There were no differences between four groups in serum profiles. Therefore, as mentioned above, it seemed that the effect of maternal protein malnutrition to fetus was able to be overcome to some extent by high protein diet intake after weaning. In conclusion, 1) Dietary protein level throughout gestation and lactation affected both nutritional status of dams and pups and milk composition: 25% ISP groups supported better nutritional status than 10% ISP group 2) It seemed that effect of dietary protein level after weaning on pups was able to be overcome the influence of maternal diet in fetus to some extent.

• Archives of Pharmacal Research
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• v.28 no.11
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• pp.1275-1281
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• 2005

The $G_{q/11}$ protein-coupled receptors, such as muscarinic (M1 & M3) receptors, have been shown to regulate the release of a soluble amyloid precursor protein (sAPP$\alpha$) produced from $\alpha$-secretase processing. However, there is no direct evidence for the precise characteristics of G proteins, and the signaling mechanism for the regulation of $G_{q/11}$ protein-coupled receptor mediated sAPP$\alpha$ release is not clearly understood. This study examined whether the muscarinic receptor-mediated release of sAPP$\alpha$ is directly regulated by $G\alpha_{q/11}$ proteins. The HEK293 cells were transiently cotransfected with muscarinic M3 receptors and a dominant-negative minigene construct of the G protein $\alpha$ subunit. The sAPP$\alpha$ release in the media was measured using an antibody specific for sAPP. The sAPP$\alpha$ release enhancement induced by muscarinic receptor stimulation was decreased by a $G_{q/11}$ minigene construct, whereas it was not blocked by a control minigene construct (the G$\alpha$ carboxy peptide in random order, G$\alpha_{q}$R) or $G\alpha_{j}$ constructs. This indicated a direct role of the $G\alpha_{q/11}$ protein in the regulation of muscarinic M3 receptor-mediated sAPP$\alpha$ release. We also investigated whether the transactivation of the epidermal growth factor receptor (EGFR) by a muscarinic agonist could regulate the sAPP$\alpha$ release in SH-SY5Y cells. Pretreatment of a specific EGFR kinase inhibitor, tyrophostin AG1478 (250 nM), blocked the EGF-stimulated sAPP$\alpha$ release, but did not block the oxoM­stimulated sAPP$\alpha$ release. This demonstrated that the transactivation of the EGFR by muscarinic receptor activation was not involved in the muscarinic receptor-mediated sAPP$\alpha$ release.