• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.5
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• pp.1019-1025
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• 1998

Proteins and polysaccharides are major food macromolecules. Generally, the mixture of these macromolecules can be separated into two phases because of their thermodynamic incompatibility. Phase separ-ation is explained by equilibrium phase diagram, which comprises binodal curve, critical point, phase separation threshold, tie-line and rectilinear diameter. Phase separation of protein-polysacc-haride solution is affected by pH, temperature, ionic strength, molecular weight, molecular structure, etc. Membraneless osmosis has been developed to concentrate protein solutions, using the phase diagram constituted by proteins and polysaccharides. Protein-polysaccharide mixtures are very promising fat mimetics because solution of mixtures forms water-continuous system with two phase-separated gels, which give plastic texture and a fatty mouthfeel.

• BMB Reports
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• v.48 no.2
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• pp.81-90
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• 2015

p73 is a structural and functional homologue of the p53 tumor suppressor protein. Like p53, p73 induces apoptosis and cell cycle arrest and transactivates p53-responsive genes, conferring its tumor suppressive activity. In addition, p73 has unique roles in neuronal development and differentiation. The importance of p73-induced apoptosis lies in its capability to substitute the pro-apoptotic activity of p53 in various human cancer cells in which p53 is mutated or inactive. Despite the great importance of p73-induced apoptosis in cancer therapy, little is known about the molecular basis of p73-induced apoptosis. In this review, we discuss the p73 structures reported to date, detailed structural comparisons between p73 and p53, and current understanding of the transcription-dependent and -independent mechanisms of p73-induced apoptosis.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.2 no.2
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• pp.63-68
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• 2016

Peptides have been developed for in vivo imaging probes against to the specific biomarker in the biological process of living systems. Peptide based imaging probes have been applied to identify and detect their active sites using imaging modalities, such as PET, SPECT and MRI. Especially, tumor receptor imaging with the peptides has been widely used to specific tumor detection. This review discusses the targeting peptides that have been successfully characterized for tumor diagnosis by receptor imaging.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.476-479
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• 2008

Understanding the dynamics of proteins is essential to gain insight into biological functions of proteins. The protein dynamics is delineated by conformational fluctuation (i.e. thermal vibration), and thus, thermal vibration of proteins has to be understood. In this paper, a simple mechanical model was considered for understanding protein's dynamics. Specifically, a mechanical vibration model was developed for understanding the large protein dynamics related to biological functions. The mechanical model for large proteins was constructed based on simple elastic model (i.e. Tirion's elastic model) and model reduction methods (dynamic model condensation). The large protein structure was described by minimal degrees of freedom on the basis of model reduction method that allows one to transform the refined structure into the coarse-grained structure. In this model, it is shown that a simple reduced model is able to reproduce the thermal fluctuation behavior of proteins qualitatively comparable to original molecular model. Moreover, the protein's dynamic behavior such as collective dynamics is well depicted by a simple reduced mechanical model. This sheds light on that the model reduction may provide the information about large protein dynamics, and consequently, the biological functions of large proteins.

• BMB Reports
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• v.50 no.5
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• pp.269-274
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• 2017

The biological activities of macrophage migration inhibitory factor (MIF) might be mediated through a classical receptor-mediated or non-classical endocytic pathway. JAB1 (C-Jun activation domain-binding protein-1) promotes the degradation of the tumor suppressor, p53, and the cyclin-dependent kinase inhibitor, p27. When MIF and JAB1 are bound to each other in various intracellular sites, MIF inhibits the positive regulatory effects of JAB1 on the activity of AP-1. The intestinal parasite, Anisakis simplex, has an immunomodulatory effect. The molecular mechanism of action of As-MIF and human JAB1 are poorly understood. In this study, As-MIF and hJAB1 were expressed and purified with high solubility. The structure of As-MIF and hJAB1 interaction was modeled by homology modeling based on the structure of Ace-MIF. This study provides evidence indicating that the MIF domain of As-MIF interacts directly with the MPN domain of hJAB1, and four structure-based mutants of As-MIF and hJAB1 disrupt the As-MIF-hJAB1 interaction.

• Proceedings of the Korean Biophysical Society Conference
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• 1996.07a
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• pp.41-41
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• 1996

Chilling-sensitive plants are damaged severly by chilling in the light. The activity of photosystem I(PSI) is known to be inhibited by low light-chilling and its iron-sulfur centers are presumed to be its primary target. In this report, the effect of chilling at 4$^{\circ}C$ in the light was investigated in the level of pigment-protein complexes in cucumber leaves compared with pea leaves. (omitted)

• BMB Reports
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• v.35 no.5
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• pp.498-507
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• 2002

A gene that encodes a thermostable protease, coined thermicin, has been isolated from Thermoanaerobacter yonseiensis that is expressed and characterized in E. coli.. In order to elucidate the molecular characteristics on thermostability of the enzyme, molecular modeling and mutagenesis technology were applied. In the modeling structure, the structural core, including the active site, was well conserved; whereas, the two loop regions were unique when compared to thermitase. The mutant enzyme with the small loop deleted (D190-I196), based on modeling structural information, showed identical enzyme activity. However, when the large loop was deleted (P233-P244), a little lower $K_m$ and even a lower kcat was found. This indicates that the large loop could influence catalytic activity. However, the unfolding temperature ($T_m$), which was determined by a differential-scanning calorimetry for the mutant enzyme deleted the small loop, was $96^{\circ}C$. This is $14^{\circ}C$ lower than that for the parent thermicin. These results suggest that the small loop may play a role in maintaining the proper folding of the enzyme at high temperatures, whereas the large loop might be related to catalysis.

• BMB Reports
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• v.57 no.6
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• pp.263-272
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• 2024

Amyloid-β (Aβ) is one of the amyloidogenic intrinsically disordered proteins (IDPs) that self-assemble to protein aggregates, incurring cell malfunction and cytotoxicity. While Aβ has been known to regulate multiple physiological functions, such as enhancing synaptic functions, aiding in the recovery of the blood-brain barrier/brain injury, and exhibiting tumor suppression/antimicrobial activities, the hydrophobicity of the primary structure promotes pathological aggregations that are closely associated with the onset of Alzheimer's disease (AD). Aβ proteins consist of multiple isoforms with 37-43 amino acid residues that are produced by the cleavage of amyloid-β precursor protein (APP). The hydrolytic products of APP are secreted to the extracellular regions of neuronal cells. Aβ 1-42 (Aβ42) and Aβ 1-40 (Aβ40) are dominant isoforms whose significance in AD pathogenesis has been highlighted in numerous studies to understand the molecular mechanism and develop AD diagnosis and therapeutic strategies. In this review, we focus on the differences between Aβ42 and Aβ40 in the molecular mechanism of amyloid aggregations mediated by the two additional residues (Ile41 and Ala42) of Aβ42. The current comprehension of Aβ42 and Aβ40 in AD progression is outlined, together with the structural features of Aβ42/Aβ40 amyloid fibrils, and the aggregation mechanisms of Aβ42/Aβ40. Furthermore, the impact of the heterogeneous distribution of Aβ isoforms during amyloid aggregations is discussed in the system mimicking the coexistence of Aβ42 and Aβ40 in human cerebrospinal fluid (CSF) and plasma.

• Archives of Pharmacal Research
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• v.29 no.5
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• pp.384-393
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• 2006

Protein carboxylmethylation methylates the free carboxyl groups in various substrate proteins by protein carboxyl O-methyltransferase (PCMT) and is one of the post-translational modifications. There have been many studies on protein carboxylmethylation. However, the precise functional role in mammalian systems is unclear. In this study, immunoglobulin, a specific form of $\gamma-globulin$, which is a well-known substrate for PCMT, was chosen to investigate the regulatory roles of protein carboxylmethylation in the immune system. It was found that the anti-BSA antibody could be carboxylmethylated via spleen PCMT to a level similar to $\gamma-globulin$. This carboxylmethylation increased the hydrophobicity of the anti-BSA antibody up to 11.4%, and enhanced the antigen-binding activity of this antibody up to 24.6%. In particular, the Fc region showed a higher methyl accepting capacity with 80% of the whole structure level. According to the amino acid sequence alignment, indeed, 7 aspartic acids and 5 glutamic acids, as potential carboxylmethylation sites, were found to be conserved in the Fc portion in the human, mouse and rabbit. The carboxylmethylation of the anti-BSA antibody was reversibly demethylated under a higher pH and long incubation time. Therefore, these results suggest that protein carboxylmethylation may reversibly regulate the antibody-mediated immunological events via the Fc region.

• Journal of Integrative Natural Science
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• v.9 no.4
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• pp.268-274
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• 2016

Filariasis causing nematode Brugia malayi is shown to harbor wolbachia bacteria as symbionts. The sequenced genome of the wolbachia endosymbiont from B.malayi (wBm) offers an unprecedented opportunity to identify new wolbachia drug targets. Hence the enzyme carbonic anhydrase from wolbachia endosymbiont of Brugia malayi (wBm) which is responsible for the reversible interconversion of carbon dioxide and water to bicarbonate and protons (or vice versa) is chosen as the drug target for filariasis. This enzyme is thought to play critical functions in bacteria by involving in various steps of their life cycle which are important for survival, The 3D structure of wBm carbonic anhydrase is predicted by selecting a suitable template using the similarity search tool, BLAST. The BLAST results shows a hexapeptide transferase family protein from Anaplasma phagocytophilum (PDB ID: 3IXC) having 77% similarity and 54% identity with wBm carbonic anhydrase. Hence the above enzyme is chosen as the template and the 3D structure of carbonic anhydrase is predicted by the tool Modeller9v7. Since the three dimensional structure of carbonic anhydrase from wolbachia endosymbiont of Brugia malayi has not yet solved, attempts were made to predict this protein. The predicted structure is validated and also molecular docking studies are carried out with the suitable inhibitors that have been solved experimentally.