• Title/Summary/Keyword: molecular interactions

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The Crystal Structure of a $\beta$-Allyl Type Phenylpropanoid 2-(4-allyl-2, 6-dimethoxyphenoxy)-1-(4-hydroxy-3-methoxyphenyl) propan-1-ol, from the Seeds of Myristica fragrans

  • Kim, Yang-Bae;Park, Il-Yeong;Kim, Jeong-Ae;Shin, Kuk-Hyun
    • Archives of Pharmacal Research
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    • v.14 no.2
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    • pp.137-142
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    • 1991
  • The structure of a $\beta$-allyl type phenylpropanoid was determined by single crystal X-ray diffraction analysis. The compound was recrystallized from a mixture of n-hexane and benzene in monoclinic crystal system with a = 24.782 (2), b = 10.537 (1), c = 7.871 (1) ${\AA}, \beta=95.74$ (1)$^\circ, $D_x$=1.216, $D_m$=1.22g/$cm^3$, space group $P2_1/a$, and Z=4. The structure was solved by direct method and refined by least-squares procedure to the final R value of 0.054 for 2824 observed reflections {$F{\geq}3\sigma(F)$}. The molecular geometry shows a most stable trans-form with respect to the bulky phenyls, and this conformation is settled by an intramolecular hydrogen bond. In the crystal, the molecules are arranged along with the screw axis, and stabilized by the $O{\cdot}H{\cdots}O$ type intermolecular hydrogen bonds. The other intermolecular contacts appear to be the normal van der Waals' interactions. The compound is a dimeric phenylpropanoid, and belongs to the neolignan analogues.

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CONSTRUCTING GENE REGULATORY NETWORK USING FREQUENT GENE EXPRESSION PATTERN MINING AND CHAIN RULES

  • Park, Hong-Kyu;Lee, Heon-Gyu;Cho, Kyung-Hwan;Ryu, Keun-Ho
    • Proceedings of the KSRS Conference
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    • v.2
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    • pp.623-626
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    • 2006
  • Group of genes controls the functioning of a cell by complex interactions. These interacting gene groups are called Gene Regulatory Networks (GRNs). Two previous data mining approaches, clustering and classification have been used to analyze gene expression data. While these mining tools are useful for determining membership of genes by homology, they don't identify the regulatory relationships among genes found in the same class of molecular actions. Furthermore, we need to understand the mechanism of how genes relate and how they regulate one another. In order to detect regulatory relationships among genes from time-series Microarray data, we propose a novel approach using frequent pattern mining and chain rule. In this approach, we propose a method for transforming gene expression data to make suitable for frequent pattern mining, and detect gene expression patterns applying FP-growth algorithm. And then, we construct gene regulatory network from frequent gene patterns using chain rule. Finally, we validated our proposed method by showing that our experimental results are consistent with published results.

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Mechanisms of radiation-induced normal tissue toxicity and implications for future clinical trials

  • Kim, Jae Ho;Jenrow, Kenneth A.;Brown, Stephen L.
    • Radiation Oncology Journal
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    • v.32 no.3
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    • pp.103-115
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    • 2014
  • To summarize current knowledge regarding mechanisms of radiation-induced normal tissue injury and medical countermeasures available to reduce its severity. Advances in radiation delivery using megavoltage and intensity-modulated radiation therapy have permitted delivery of higher doses of radiation to well-defined tumor target tissues. Injury to critical normal tissues and organs, however, poses substantial risks in the curative treatment of cancers, especially when radiation is administered in combination with chemotherapy. The principal pathogenesis is initiated by depletion of tissue stem cells and progenitor cells and damage to vascular endothelial microvessels. Emerging concepts of radiation-induced normal tissue toxicity suggest that the recovery and repopulation of stromal stem cells remain chronically impaired by long-lived free radicals, reactive oxygen species, and pro-inflammatory cytokines/chemokines resulting in progressive damage after radiation exposure. Better understanding the mechanisms mediating interactions among excessive generation of reactive oxygen species, production of pro-inflammatory cytokines and activated macrophages, and role of bone marrow-derived progenitor and stem cells may provide novel insight on the pathogenesis of radiation-induced injury of tissues. Further understanding the molecular signaling pathways of cytokines and chemokines would reveal novel targets for protecting or mitigating radiation injury of tissues and organs.

Phase Transition of Octaneselenolate Self-assembled Monolayers on Au(111) Studied by Scanning Tunneling Microscopy

  • Choi, Jung-Seok;Kang, Hun-Gu;Ito, Eisuke;Hara, Masahiko;Noh, Jae-Geun
    • Bulletin of the Korean Chemical Society
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    • v.32 no.8
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    • pp.2623-2627
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    • 2011
  • We investigated the surface structure and wetting behavior of octaneselenolate self-assembled monolayers (SAMs) on Au(111) formed in a 50 ${\mu}M$ ethanol solution according to immersion time, using scanning tunneling microscopy (STM) and an automatic contact angle (CA) goniometer. Closely-packed, well-ordered alkanethiol SAMs would form as the immersion time increased; unexpectedly, however, we observed the structural transition of octaneselenolate SAMs from a molecular row phase with a long-range order to a disordered phase with a high density of vacancy islands (VIs). Molecularly resolved STM imaging revealed that the missing-row ordered phase of the SAMs could be assigned as a $(6{\times}{\surd}3)R30^{\circ}$ superlattice containing three molecules in the rectangular unit cell. In addition, CA measurements showed that the structural order and defect density of VIs are closely related to the wetting behaviors of octaneselenolate SAMs on gold. In this study, we clearly demonstrate that interactions between the headgroups and gold surfaces play an important role in determining the physical properties and surface structure of SAMs.

Molecular cloning and expression analysis of a C-type lectin in the rock bream, Oplegnathus fasciatus

  • Kwon, Mun-Gyeong;Kim, Ju-Won;Park, Myoung-Ae;Hwang, Jee-Youn;Park, Hyung-Jun;Park, Chan-Il
    • Journal of fish pathology
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    • v.25 no.1
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    • pp.11-20
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    • 2012
  • C-type lectins are crucial for pathogen recognition, innate immunity, and cell-cell interactions. In this study, a C-type lectin gene was cloned from the rock bream. The full-length RbCTL cDNA was 729 bp with a 429 bp ORF encoding a 164-residue protein. The deduced amino acid sequence of RbCTL had all of the conserved features crucial for its fundamental structure, including the four cysteine residues involved in sulfide bridge formation and potential $Ca^2+$/carbohydrate-binding sites. RbCTL contains a signal peptide one single carbohydrate recognition domain. It showed 29.4% similarity to the C-type lectin of rainbow trout. RbCTL mRNA was predominately expressed in gill and head-kidney tissue and expressed less in peripheral blood leukocytes, trunk-kidney, spleen, liver, intestine and muscle. Expression of RbCTL was differentially upregulated in rock bream stimulated with LPS, Con A/PMA and poly I:C.

Complexation of Co-contaminant Mixtures between Silver(I) and Polycyclic Aromatic Hydrocarbons

  • Yim, Soo-Bin
    • Journal of Environmental Science International
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    • v.12 no.8
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    • pp.871-879
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    • 2003
  • The complexation of co-contaminant mixtures between Ag(I) and polycyclic aromatic hydrocarbon (PAH) molecules (naphthalene, pyrene, and perylene) were investigated to quantify the equilibrium constants of their complexes and elucidate the interactions between Ag(I) and PAH molecules. The apparent solubilities of PAHs in aqueous solutions increased with increasing Ag(I) ion concentration. The values, K$_1$ and K$_2$ of equilibrium constants of complexes of Ag(I)-PAHs, were 2.990 and 0.378, 3.615 and 1.261, and 4.034 and 1.255, for naphthalene, pyrene, and perylene, respectively, The K$_1$and K$_2$ values of PAHs for Ag(I) increased in the order of naphthalene < pyrene < perylene and naphthalene < pyrene ≒ perylene, respectively, indicating that a larger size of PAH molecule is likely to have more a richer concentration of electrons on the plane surfaces which can lead to stronger complexes with the Ag(I) ion. For the species of Ag(I)-PAH complexes, a 1:1 Ag(I) : the aromatic complex, AgAr$\^$+/, was found to be a predominant species over a 2:1 Ag(I) : aromatic complex, Ag$_2$Ar$\^$++/. The PAH molecules with four or more aromatic rings and/or bay regions were observed to have slightly less affinity with the Ag(I) ion than expected, which might result from inhibiting forces such as the spread of aromatic $\pi$ electrons over o wide molecular surface area and the intermolecular electronic repulsion in bay regions.

Zinc in Pancreatic Islet Biology, Insulin Sensitivity, and Diabetes

  • Maret, Wolfgang
    • Preventive Nutrition and Food Science
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    • v.22 no.1
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    • pp.1-8
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    • 2017
  • About 20 chemical elements are nutritionally essential for humans with defined molecular functions. Several essential and nonessential biometals are either functional nutrients with antidiabetic actions or can be diabetogenic. A key question remains whether changes in the metabolism of biometals and biominerals are a consequence of diabetes or are involved in its etiology. Exploration of the roles of zinc (Zn) in this regard is most revealing because 80 years of scientific discoveries link zinc and diabetes. In pancreatic ${\beta}$- and ${\alpha}$-cells, zinc has specific functions in the biochemistry of insulin and glucagon. When zinc ions are secreted during vesicular exocytosis, they have autocrine, paracrine, and endocrine roles. The membrane protein ZnT8 transports zinc ions into the insulin and glucagon granules. ZnT8 has a risk allele that predisposes the majority of humans to developing diabetes. In target tissues, increased availability of zinc enhances the insulin response by inhibiting protein tyrosine phosphatase 1B, which controls the phosphorylation state of the insulin receptor and hence downstream signalling. Inherited diseases of zinc metabolism, environmental exposures that interfere with the control of cellular zinc homeostasis, and nutritional or conditioned zinc deficiency influence the pathobiochemistry of diabetes. Accepting the view that zinc is one of the many factors in multiple gene-environment interactions that cause the functional demise of ${\beta}$-cells generates an immense potential for treating and perhaps preventing diabetes. Personalized nutrition, bioactive food, and pharmaceuticals targeting the control of cellular zinc in precision medicine are among the possible interventions.

Specific Recognition of Unusual DNA Structures by Small Molecules: An Equilibrium Binding Study

  • Suh, Dong-Chul
    • BMB Reports
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    • v.29 no.1
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    • pp.1-10
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    • 1996
  • The binding interaction of ethidium to a series of synthetic deoxyoligonucleotides containing a B-Z junction between left-handed Z-DNA and right-handed B-DNA, was studied. The series of deoxyoligonucleotides was designed so as to vary a dinucleotide step immediately adjacent to a B-Z junction region. Ethidium binds to the right-handed DNA forms and hybrid B-Z forms which contain a B-Z junction, in a highly cooperative manner. In a series of deoxyoligonucleotides, the binding affinity of ethidium with DNA forms which were initially hybrid B-Z forms shows over an order of magnitude higher than that with any other DNA forms, which were entirely in B-form DNA The cooperativity of binding isotherms were described by an allosteric binding model and by a neighbor exclusion model. The binding data were statistically compared for two models. The conformation of allosterically converted DNA forms under binding with ethidium is found to be different from that of the initial B-form DNA as examined by CD spectra. The ratio of the binding constant was interestingly correlated to the free energy of base unstacking and the conformational conversion of the dinucleotide. The more the base stacking of the dinucleotide is unstable, or the harder the conversion of B to A conformation, the higher the ratio of the binding constant of ethidium with the allosterically converted DNA forms and with the initial B-Z hybrid forms. DNA sequence around a B-Z junction region affects the binding affinity of ethidium. The results in this study demonstrate that ethidium could preferentially interact with unusual DNA structures.

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Phosphorylation-dependent regulation of Notch1 signaling: the fulcrum of Notch1 signaling

  • Lee, Hye-Jin;Kim, Mi-Yeon;Park, Hee-Sae
    • BMB Reports
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    • v.48 no.8
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    • pp.431-437
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    • 2015
  • Notch signaling plays a pivotal role in cell fate determination, cellular development, cellular self-renewal, tumor progression, and has been linked to developmental disorders and carcinogenesis. Notch1 is activated through interactions with the ligands of neighboring cells, and acts as a transcriptional activator in the nucleus. The Notch1 intracellular domain (Notch1-IC) regulates the expression of target genes related to tumor development and progression. The Notch1 protein undergoes modification after translation by posttranslational modification enzymes. Phosphorylation modification is critical for enzymatic activation, complex formation, degradation, and subcellular localization. According to the nuclear cycle, Notch1-IC is degraded by E3 ligase, FBW7 in the nucleus via phosphorylation-dependent degradation. Here, we summarize the Notch signaling pathway, and resolve to understand the role of phosphorylation in the regulation of Notch signaling as well as to understand its relation to cancer. [BMB Reports 2015; 48(8): 431-437]

Construction and Characterization of Escherichia coli-Corynebacterium nephridii Hybrid Thioredoxins

  • Sa, Jae-Hoon;Kim, Kyung-Hoon;Lim, Chang-Jin
    • BMB Reports
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    • v.28 no.1
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    • pp.51-56
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    • 1995
  • Thioredoxin is a small redox protein with an active-site disulfide/dithiol, and is ubiquitous in bacteria, plants, and animals. To investigate the structure-function relationship of thioredoxin, the genes encoding Escherichia coli thioredoxin and Corynebacterium nephridii thioredoxin C3 were fused via a common restriction site in the nucleotide sequence coding for the active site of the proteins to generate two chimeric thioredoxins, designated E-C3(N to C-terminal) and C3-E. The hybrid thioredoxin genes were put under the T7 promoter and their productions were confirmed. The two hybrid thioredoxins complemented phenotypes of a thioredoxin-deficient E. coli strain. A strain containing the C3-E hybrid thioredoxin supported growth of the T7 phage, whereas a strain expressing the E-C3 hybrid thioredoxin did not. However, both hybrids supported growth of M13 phages. The two hybrid thioredoxins were also characterized in other aspects. Differences in activity between the hybrid thioredoxins were attributed to altered interactions of the N- and C-terminal domains of the molecule, which produced changes in the three-dimensional structure of the active site region.

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