• 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.

• Biomolecules & Therapeutics
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• v.25 no.3
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• pp.223-230
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• 2017

Platelets play an essential role in hemostasis through aggregation and adhesion to vascular injury sites but their unnecessary activation can often lead to thrombotic diseases. Upon exposure to physical or biochemical stimuli, remarkable platelet shape changes precede aggregation or adhesion. Platelets shape changes facilitate the formation and adhesion of platelet aggregates, but are readily reversible in contrast to the irrevocable characteristics of aggregation and adhesion. In this dynamic phenomenon, complex molecular signaling pathways and a host of diverse cytoskeleton proteins are involved. Platelet shape change is easily primed by diverse pro-thrombotic xenobiotics and stimuli, and its inhibition can modulate thrombosis, which can ultimately contribute to the development or prevention of thrombotic diseases. In this review, we discussed the current knowledge on the mechanisms of platelet shape change and also pathological implications and therapeutic opportunities for regulating the related cytoskeleton dynamics.

• Journal of Applied Biological Chemistry
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• v.65 no.1
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• pp.57-62
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• 2022

Excessive activation and aggregation of platelets is a major cause of cardiovascular disease. Therefore, inhibition of platelet activation and aggregation is considered an attractive therapeutic target in preventing and treating cardiovascular diseases. In particular, strong platelet activation and aggregation by collagen secreted from the vascular endothelium are characteristic of vascular diseases. Artesunate is a compound extracted from the plant roots of Artemisia or Scopolia species, and has been reported to be effective in anticancer and Alzheimer's disease fields. However, the effect and mechanism of artesunate on collagen-induced platelet activation and aggregation have not been elucidated. In this study, the effect of artesunate on collagen-induced human platelet aggregation was confirmed and the mechanism of action of artesunate was clarified. Artesunate inhibited the phosphorylation of PI3K/Akt and Mitogen-activated protein kinases, which are phosphoproteins that are known to act in the signal transduction process when platelets are activated. In addition, artesunate decreased TXA₂ production and decreased granule secretion in platelets such as ATP and serotonin release. As a result, artesunate strongly inhibited platelet aggregation induced by collagen, a strong aggregation inducer secreted from vascular endothelial cells, with an IC₅₀ of 106.41 µM. These results suggest that artesunate has value as an effective antithrombotic agent for inhibiting the activation and aggregation of human platelets through vascular injury.

• Preventive Nutrition and Food Science
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• v.7 no.2
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• pp.184-187
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• 2002

Blood products from slaughterhouses that are not hygienically prepared for disposal or food consumption pose a human health hazard. Gamma irradiation is an effective method for sterilization of blood products, but may introduce changes in the molecular characteristics of proteins. This study evaluated the effects of irradiation on animal plasma proteins. Bovine and porcine blood was obtained from a slaughterhouse and the plasma proteins purified and lyophilized. The secondary structure and molecular weight distribution of the plasma protein solutions and powders were examined after ${\gamma}$-irradiation at 1, 5, 7 and 10 kGy. Gamma-irradiation affected the molecular properties of the protein solutions, but not the protein powders. Circular dichroism and sodium dodecyl sulfate-polyacrylamide gel electrophoresis studies showed that increased doses of ${\gamma}$-irradiation decrease the ordered structure of plasma proteins in solution, and cause initial fragmentation of the polypeptide chains and subsequent aggregation.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.165-166
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• 1996

A bottom-up model for the formation of GMCs is described, where the observed GMCs are the aggregates of less massive clouds. The aggregates are getting more and more massive in the process of consecutive collision between clouds.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.227-237
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• 2002

A numerical technique for simulating the aggregation of charged particles was presented with a Brownian dynamic simulation in the free molecular regime. The Langevin equation was used for tracking each particle making up an aggregate. A periodic boundary condition was used for calculation of the aggregation process in each cell with 500 primary particles of 16 nm in diameter. We considered the thermal force and the electrostatic force for the calculation of the particle motion. The electrostatic force on a particle in the simulation cell was considered as a sum of electrostatic forces from other particles in the original cell and its replicate cells. We assumed that the electric charges accumulated on an aggregate were located on its center of mass, and aggregates were only charged with pre-charged primary particles. The morphological shape of aggregates was described in terms of the fractal dimension. In the simulation, the fractal dimension for the uncharged aggregate was D$\_$f/ = 1.761. The fractal dimension changed slightly for the various amounts of bipolar charge. However, in case of unipolar charge, the fractal dimension decreased from 1.641 to 1.537 with the increase of the average number of charges on the particles from 0.2 to 0.3 in initial states. In the bipolar charge state, the average sizes of aggregates were larger than that of the uncharged state in the early and middle stages of aggregation process, but were almost the same as the case of the uncharged state in the final stage. On the other hand, in the unipolar charge state, the average size of aggregates and the dispersion of particle volume decreased with the increasing of the charge quantities.

• Natural Product Sciences
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• v.29 no.1
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• pp.42-49
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• 2023

This study investigated the effect of ethanol extracts of horsetail, alfalfa, ortie, chêne and aleppo oak on blood coagulation in vitro. Extraction was performed by the maceration method. Extracts were mixed with platelet and plasma, then prothrombin time (PT), activated partial thromboplastin time (APTT) and platelet aggregation tests were conducted. Alfalfa extract had a dose-dependent effect on the PT. Ortie, and horsetail, reduced the PT significantly compared to control group. Alfalfa, horsetail, and ortie reduced the APTT, but their effect was insignificant compared to the control group. The pooled extract showed the highest effect compared to the single extracts in a dose-dependent manner. Horsetail and alfalfa induced platelet aggregation in response to arachidonic acid but not in response to collagen. In the case of ortie, no aggregation occurred regarding the arachidonic acid, and incomplete was observed in response to collagen. Interestingly, blood clotting occurred immediately after adding the chêne, aleppo oak and the pooled extract, and therefore platelet poor plasma (PPP) and platelet rich plasma (PRP) became jelly. Generally, chêne and aleppo oak, as well as pooled extract, were more effective in inducing both primary and secondary coagulation pathways via shortening the PT and APTT, and induction of platelet aggregation.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.848-854
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• 2012

We have studied the oligomerization of a fibril-forming segment of ${\alpha}$-Synulcein using a replica exchange molecular dynamics (REMD) simulation. The simulation was performed with trimers and tetramers of a 12 amino acid residue stretch (residues 71-82) of ${\alpha}$-Synulcein. From extensive REMD simulations, we observed the spontaneous formation of both trimer and tetramer, demonstrating the self-aggregating and fibril-forming properties of the peptides. Secondary structure profile and clustering analysis illustrated that antiparallel ${\beta}$-sheet structures are major species corresponding to the global free energy minimum. As the size of the oligomer increases from a dimer to a tetramer, conformational stability is increased. We examined the evolution of simple order parameters and their free energy profiles to identify the process of aggregation. It was found that the degree of aggregation increased as time passed. Tetramer formation was slower than trimer formation and a transition in order parameters was observed, indicating the full development of tetramer conformation which is more stable than that of the trimer. The shape of free energy surface and change of order parameter distributions indicate that the oligomer formation follows a dock-and-lock process.

• BMB Reports
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• v.42 no.12
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• pp.812-816
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• 2009

To screen chaperone proteins from Schizosaccharomyce pombe (S. pombe), we prepared recombinant citrate synthase of the fission yeast as a substrate of anti-aggregation assay. Purified recombinant citrate synthase showed citrate synthase activity and was suitable for the substrate of chaperone assay. Several heat stable proteins including aspartyl aminopeptidase (AAP) for candidates of chaperone were screened from the supernatant fraction of heat-treated crude extract of S. pombe. The purified AAP migrated as a single band of 47 kDa on SDS-polyacrylamide gel electrophoresis. The native size of AAP was estimated as 200 kDa by a HPLC gel permeation chromatography. This enzyme can remove the aspartyl residue at N-terminus of angiotensin I. In addition, AAP showed the heat stability and protected the aggregation of citrate synthase caused by thermal denaturation. This study showed that S. pombe AAP is a moonlight protein that has aspartyl aminopeptidase and chaperone activities.

• Applied Biological Chemistry
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• v.51 no.3
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• pp.183-187
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• 2008

Alkyl thiosulfi(o)nates, analogs of allyl-2-propene-1-thiosulfinate isolated from Allium sativum and having antibacterial activity, were chemically synthesized and their biological activities were investigated. Alkyl thiosulfinates were prepared by oxidation of corresponding disulfides with organic peroxy acid, while alkyl thiosulfonates could be obtained by oxidation of the alkyl thiosulfinates using sodium periodate. All synthetic thiosulfi(o)nates showed antibacterial activity against Staphylococcus aureus B33 and antifungal activity against Candida utilis ATCC42416. Further more synthetic alkyl thiosulfonates displayed antioxidant activity and have also prevention effect of platelet aggregation induced by collagen in rat.