• Genomics & Informatics
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• v.9 no.2
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• pp.74-78
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• 2011

Numerous restraints and simplifications have been developed for methods that anticipate protein structure to reduce the colossal magnitude of possible conformational states. In this study, we investigated if globularity is a general characteristic of proteins and whether they can be applied as a valid constraint in protein structure simulations with approximated measurements (Gb-index). Unexpectedly, most of the proteins showed strong structural globularity (i.e., mode of approximately 76% similarity to the perfect globe) with only a few percent of proteins being outliers. Small proteins tended to be significantly non-globular ($R^2$=0.79) and the minimum Gb-index showed a logarithmic increase with the increase in protein size ($R^2$=0.62), strongly implying that the non-globular characteristics might be more acceptable for smaller proteins than larger ones. The strong perfect globe-like character and the relationship between small size and the loss of globular structure of a protein may imply that living organisms have mechanisms to aid folding into the globular structure to reduce irreversible aggregation. This also implies the possible mechanisms of diseases caused by protein aggregation, including some forms of trinucleotide repeat expansion-mediated diseases.

• BMB Reports
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• v.39 no.3
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• pp.335-338
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• 2006

Methylglyoxal (MG) is an endogenous physiological metabolite which is present in increased concentrations in diabetics. MG reacts with the amino acids of proteins to form advanced glycation end products. In this in vitro study, we investigated the effect of MG on the structure and function of ceruloplasmin (CP) a serum oxidase carrier of copper ions in the human. When CP was incubated with MG, the protein showed increased electrophoretic mobility which represented the aggregates at a high concentration of MG (100 mM). MG-mediated CP aggregation led to the loss of enzymatic activity and the release of copper ions from the protein. Radical scavengers and copper ion chelators significantly prevented CP aggregation. CP is an important protein that circulates in plasma as a major copper transport protein. It is suggested that oxidative damage of CP by MG may induce perturbations of the copper transport system and subsequently lead to harmful intracellular condition. The proposed mechanism, in part, may provide an explanation for the deterioration of organs in the diabetic patient.

• 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.

• Macromolecular Research
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• v.11 no.4
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• pp.241-249
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• 2003

A molecular-thermodynamic model to describe the salt-induced protein precipitation is developed based on the perturbation theory. We employed the modified perturbed hard-sphere-chain (PHSC) equation of state for copolymer mixtures to take into account the pre-aggregation effect among protein particles. Hypothetical pressure-composition diagrams are computed with various size differences and salt concentrations. The precipitation behaviors are also studied for various types of pre-aggregation effect for the given systems.

• Journal of Applied Biological Chemistry
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• v.63 no.2
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• pp.131-136
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• 2020

When blood vessels are damaged, a fast hemostatic response should occur to minimize blood loss and maintain normal circulation. Platelet activation and aggregation are essential in this process. However, excessive platelet aggregation or abnormal platelet aggregation may be the cause of cardiovascular diseases such as thrombosis, stroke, and atherosclerosis. Therefore, finding a substance capable of regulating platelet activation and suppressing agglutination reaction is important for the prevention and treatment of cardiovascular diseases. 6,7-Dimethoxy-2H-chromen-2-one (Scoparone), found primarily in the roots of Artemisia or Scopolia plants, has been reported to have a pharmacological effect on immunosuppression and vasodilation, but studies of platelet aggregation and its mechanisms are still insufficient. This study confirmed the effect of scoparone on collagen-induced human platelet aggregation, TXA₂ production, and major regulation of intracellular granule secretion (ATP and serotonin release). In addition, the effect of scoparone on the phosphorylation of the phosphoproteins PI3K/Akt and mitogen-activated protein kinases (MAPK) involved in signal transduction in platelet aggregation was studied. As a result, scoparone significantly inhibited the phosphorylation of PI3K/Akt and MAPK, which significantly inhibited platelet aggregation through TXA₂ production and intracellular granule secretion (ATP and serotonin release). Therefore, we suggest that scoparone is an antiplatelet substance that regulates the phosphorylation of phosphoproteins such as PI3K/Akt and MAPK and is of value as a preventive and therapeutic agent for platelet-derived cardiovascular disease.

• BMB Reports
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• v.38 no.4
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• pp.407-413
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• 2005

Calcium and zinc binding protein, calprotectin is a multifunctional protein with broad spectrum antimicrobial and antitumoural activity. It was purified from human neutrophil, using a two-step ion exchange chromatography. Since surface hydrophobicity of calprotectin may be important in membrane anchoring, membrane penetration, subunits oligomerization and some biological roles of protein, in this study attempted to explore the effect of calcium in physiological range on the calprotectin lipophilicity. Incubation of human calprotectin ($50\;{\mu}g/ml$) with different calcium concentrations showed that 1-anilino-8-naphthalene sulfonic acid (ANS) fluorescence intensity of the protein significantly elevates with calcium in a dose dependent manner, suggesting an increase in calprotectin surface hydrophobicity upon calcium binding. Our study also indicates that calcium at higher concentrations (6, 8 and 10 mM) induces aggregation of human calprotectin. Our finding demonstrates that the starting time and the rate constant of calprotectin aggregation depend on the calcium concentration.

• KSBB Journal
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• v.31 no.1
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• pp.66-72
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• 2016

Chinese hamster ovary (CHO) cells have been widely used for production of various recombinant proteins such as cytokines and monoclonal antibodies. The cell aggregation and cell death in CHO cell culture directly affect cell viability, and productivity and quality of products. In this study, we investigated preventing effects of storage-protein 2 (SP2) derived from silkworm hemolymph on cell aggregation and cell death in CHO cell culture producing albuminerythropoietin (Alb-EPO). The viable cell density in the culture supplemented with 2 mg/mL SP2 was 1.71-fold higher than that in control culture. Increased titer of Alb-EPO was also found in the culture with SP2. Morphology of CHO cells in SP2 supplemented cultures did not differ from that of control. In addition, the cell aggregation rate of the SP2 cultures was reduced 20% compared to the control. Finally, we confirmed that the apoptosis was strongly suppressed by addition of SP2 in the cultures. These results clearly demonstrate that SP2 can be served as an effective supplement for enhancing titer of Alb-EPO via reducing cell aggregation and cell death.

• 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.

• Food Science of Animal Resources
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• v.41 no.5
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• pp.855-868
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• 2021

The present study was designed to investigate the effects of protein formula with different casein (C) to whey protein (W) ratios on dispersion stability, protein quality and body composition in rats. Modification of the casein to whey protein (CW) ratio affected the extent of protein aggregation, and heated CW-2:8 showed a significantly increased larger particle (>100 ㎛) size distribution. The largest protein aggregates were formed by whey protein self-aggregation. There were no significant differences in protein aggregation when the CW ratios changed from 10:0 to 5:5. Based on the protein quality assessment (CW-10:0, CW-8:2, CW-5:5, and CW-2:8) for four weeks, CW-10:0 showed a significantly higher feed intake (p<0.05), but the high proportion of whey protein in the diet (CW-5:5 and CW-2:8) increased the feed efficiency ratio, protein efficiency ratio, and net protein ratio compared to other groups. Similarly, CW-2:8 showed greater true digestibility compared to other groups. No significant differences in fat mass and lean mass analyzed by dual-energy x-ray absorptiometry were observed. A significant difference was found in the bone mineral density between the CW-10:0 and CW-2:8 groups (p<0.05), but no difference was observed among the other groups. Based on the results, CW-5:5 improved protein quality without causing protein instability problems in the dispersion.

• Biomedical Science Letters
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• v.20 no.3
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• pp.129-138
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• 2014

In this study, we investigated the effect of water extract from rice bran (RB) on ADP ($20{\mu}M$)-stimulated platelet aggregation. RB dose-dependently inhibited ADP-induced platelet aggregation, and its $IC_{50}$ value was $224.0{\mu}g/mL$, which was increased by adenylate cyclase inhibitor SQ22536 and cAMP-dependent protein kinase (A-kinase) inhibitor Rp-8-Br-cAMPS. RB elevated the phosphorylation of VASP ($Ser^{157}$) which was also inhibited by SQ22536 and Rp-8-Br-cAMPS. It is thought that RB-elevated cAMP contributed to the phosphorylation of VASP ($Ser^{157}$) to inhibit ADP-induced platelet aggregation. Therefore, we demonstrate that RB has an antiplatelet effect via cAMP-dependent phosphorylation of VASP ($Ser^{157}$), and RB may have preventive or therapeutic potential for platelet aggregation-mediated diseases, such as thrombosis, myocardial infarction, atherosclerosis, and ischemic cerebrovascular disease.