• Bulletin of the Korean Chemical Society
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• v.11 no.3
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• pp.235-238
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• 1990

Complexes of the type[Co(T)(L-pro)], where T is the quadridentate $N_2O_2$-type ligand, N,N'-dimethylethylenediamine-N,N'-diacetate or N,N'-dimethylethylenediamine-N,N'-di-$\alpha$-butyrate, have been prepared. The complexes were separated into the two stereoisomers, $\Delta$-s-cis-[Co(T)(L-pro)] and $\Lambda$-s-cis-[Co(T)(L-pro)]. They were characterized by their proton magnetic resonance, absorption and circular dichroism spectra, elemental analyses.

• International Journal of Industrial Entomology and Biomaterials
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• v.19 no.2
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• pp.255-258
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• 2009

Structure and Properties of sericinjam sericin extracted was investigated using SDS-PAGE electrophoresis, UV, CD, and DSC. The molecular weight and its distribution of sericinjam sericin showed broad tailing pattern. Circular dichlroism spectra showed that the structure of sericinjam sericin in solution was different with domestic one. However, differential thermal calorimetric properties are similar to each other.

• Journal of the Korean Magnetics Society
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• v.26 no.5
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• pp.149-153
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• 2016

In Fe/Gd multilayers, patterning effect on the interlayer coupling was studied by comparing patterned and unpatterned samples that were cut from a multilayer film. A comparative study of the two samples via temperature dependent Gd-specific magnetization vector using X-ray magnetic circular dichroism (XMCD) shows that the temperature dependence of the Gd magnetization vector can be modified in the patterned sample due to a competition between the patterning and antiferromagnetic interlayer coupling effects.

• Current Optics and Photonics
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• v.3 no.4
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• pp.275-284
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• 2019

Chirality is ubiquitous in physics and biology from microscopic to macroscopic phenomena, such as fermionic interactions and DNA duplication. In photonics, chirality has traditionally represented differentiated optical responses for right and left circular polarizations. This definition of optical chirality in the polarization domain includes handedness-dependent phase velocities or optical absorption inside chiral media, which enable polarimetry for measuring the material concentration and circular dichroism spectroscopy for sensing biological or chemical enantiomers. Recently, the emerging field of non-Hermitian photonics, which explores exotic phenomena in gain or loss media, has provided a new viewpoint on chirality in photonics that is not restricted to the traditional polarization domain but is extended to other physical quantities such as the orbital angular momentum, propagation direction, and system parameter space. Here, we introduce recent milestones in chiral light-matter interactions in non-Hermitian photonics and show an enhanced degree of design freedom in photonic devices for spin and orbital angular momenta, directionality, and asymmetric modal conversion.

• Current Applied Physics
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• v.18 no.11
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• pp.1185-1189
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• 2018

Thickness-dependent magnetic domain structure of ultrathin Co wedge films (0.3 nm-1.0 nm) sandwiched by Pt layers was investigated by scanning transmission x-ray microscopy (STXM) employing X-ray magnetic circular dichroism (XMCD), utilizing elliptically polarized soft x-rays and electromagnetic fields, with a spatial resolution of 50 nm. The magnetic domain images measured at the Co $L_3$ edge showed the evolution of the magnetic domain structures from maze-like form to the bubble-like form as the perpendicular magnetic field was applied. The asymmetric domain expansion of a 500 nm-scale bubble domain was also measured when the in-plane and perpendicular external magnetic field were applied simultaneously.

• Journal of the Korean Chemical Society
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• v.58 no.5
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• pp.456-462
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• 2014

Binary-doped conducting chiral polyaniline (PAni) was synthesized by electrochemical polymerization of aniline at low-temperature ($0^{\circ}C$) and room-temperature (RT) conditions. (+)-Camphorsulfonic acid (CSA) and hydrochloric acid (HCl) were used as a binary dopant. Formation of the binary-doped PAni rather than a mixture of the corresponding single-doped PAni was confirmed by cyclic voltammogram, FT-IR and circular dichroism spectra. The temperature influenced the electrochemical behavior and doping level, thus determining the crystallinity and morphology of the PAni. However, among other results, morphology of the PAni is found to be most strongly depends on the polymerization temperature. With increased temperature from the initial state to RT, morphology of the PAni changed from fibrous to short-fibrous structure. The sheet resistance of the PAni films on an ITO was measured by using four-point probe dc method.

• Journal of the Korean Magnetic Resonance Society
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• v.19 no.2
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• pp.74-82
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• 2015

Ryanodine receptor (RyR) is one of the two major $Ca^{2+}$ channels in membranes of intracellular $Ca^{2+}$ stores and is found in sarcoplasmic reticulum (SR), endoplasmic reticulum (ER). RyR1 is also the major calmodulin-binding protein of sarcoplasmic reticulum membranes. Residues 4064-4210 in the RyR1 polypeptide chain has similar primary sequence with calmodulin (CaM) and was designated as CaM-like domain (CaMLD). When expressed as a recombinant peptide, CaMLD showed several CaM-like properties in previous studies. Still, previous studies of CaMLD were focused on protein-protein interactions rather than its own properties. Here, we studied the expression of CaMLD and its sub-domains corresponding to each lobe of CaM in Escherichia coli. CaMLD could be obtained only as inclusion body, and it was refolded using urea solubilization followed by dialysis. Using spectroscopic approaches, such as NMR, circular dichroism, and gel filtration experiment, we found that the refolded CaMLD exists as nonspecific aggregate, even though it has alpha helical secondary structure. In comparison, the first half of CaMLD (R4061-4141) could be obtained as natively soluble protein with thioredoxin fusion. After the removal of the fusion tag, it exhibited folded and helical properties as shown by NMR and circular dichroism experiments. Its oligomeric status was different from CaMLD, existing as dimeric form in solution. However, the second half of the protein could not be obtained as soluble protein regardless of fusion tag. Based on these results, we believe that CaMLD, although similar to CaM in sequence, has quite different physicochemical properties and that the second half of the protein renders it the aggregative properties.

• Journal of the Korean Magnetic Resonance Society
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• v.9 no.1
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• pp.38-47
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• 2005

Axin is a scaffold protein of the APC/axin/GSK complex, binding to all of the other signalling components. Axin interacts with Glycogen synthase kinase 3$\beta$ (GSK 3$\beta$) and functions as a negative regulator of Wnt signalling pathways. To determine the solution structure of the GSK3$\beta$ binding regions of the axin, we initiated NMR study of axin fragment comprising residues 3$Val^{388} - Arg^{401}$using circular dichroism (CD) and two-dimensional NMR spectroscopy. The CD spectra of 3$axin^{pep}$ in the presence of 30% TFE displayed a standard 3$\alpha$-helical conformation, exhibiting the bound structure of 3$axin^{pep}$ to GSK3$\bata$. On the basis of experimental restraints including $NOE_s$, and $^3J_{HN\alpha} $ coupling constants, the solution conformation of $axin^{pep}$ was determined with program CNS. The 20 lowest energy structures were selected out of 50 final simulated-annealing structures in both water and TFE environment, respectively. The $RMSD_s$ for the 20 structures in TFE solution were 0.086 nm for backbone atoms and 0.195 nm for all heavy atoms, respectively. The Ramachandran plot indicates that the $\varphi$, $\psi$ angles of the 20 final structures is properly distributed in energetically acceptable regions. $Axin^pep$ in aqueous solutions consists of a stable $\alpha$-helix spanning residues form $Glu^{391}$ to $Val^{391} $, which is an interacting motif with GSK3$\beta$.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.310-319
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• 1982

Cobalt(III) complexes with sexidentate ligands, N,N,N',N'-tetrakis(2-amino-ethyl)-1,2-ethanediamine (ten), -1,3-propanediamine (ttn), -1,4-butanediamine (ttmd), -(R,R)-and -(R,S)-2,4-pentanediamine (tptn) were prepared, and the characterization of d-d absorption band on the variation of chelate ring size and conformation of these complexes were studied by means of electronic spectra. The first d-d absorption bands of $[Co(L)]^{3+}$ complexes are shifted to smaller wave numbers in the order. ttn > (R,R)-tptn > ten > ttmd${\simeq}$(R,S)-tptn for (L). The UV, $^{13}C$ NMR, and Circular Dichroism studies indicate that the R,S-tptn ligand of $[Co(R,S-tptn)]^{3+}$ complex coodinates to cobalt(Ⅲ) ion as a sexidentate with one methyl group in axial position.

• BMB Reports
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• v.47 no.11
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• pp.625-630
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• 2014

Defensins, which are small cationic molecules produced by organisms as part of their innate immune response, share a common structural scaffold that is stabilized by three disulfide bridges. Coprisin is a 43-amino acid defensin-like peptide from Copris tripartitus. Here, we report the intramolecular disulfide connectivity of cysteine-rich coprisin, and show that it is the same as in other insect defensins. The disulfide bond pairings of coprisin were determined by combining the enzymatic cleavage and mass analysis. We found that the loss of any single disulfide bond in coprisin eliminated all antibacterial, but not antifungal, activity. Circular dichroism (CD) analysis showed that two disulfide bonds, Cys20-Cys39 and Cys24-Cys41, stabilize coprisin's ${\alpha}$-helical region. Moreover, a BLAST search against UniProtKB database revealed that coprisin's ${\alpha}$-helical region is highly homologous to those of other insect defensins.