• Journal of the Korean Magnetic Resonance Society
• /
• v.26 no.4
• /
• pp.59-65
• /
• 2022

Benzo[a]pyrene (BaP), one of the polycyclic aromatic hydrocarbons (PAHs), is an endocrine disruptor and carcinogenic. This study was conducted to investigate the metabolic changes of zebrafish short-term exposure to BaP using nuclear magnetic resonance (NMR) spectroscopy. In our results, the multivariate analysis showed that the metabolic responses were differed according to the exposure concentration. Also, it was observed that exposure to high concentration of BaP (162 ㎍/L and 1620 ㎍/L) increased the levels of creatine, histidine, and inosine in zebrafish, which means high concentration of BaP exposure affected the energy metabolism and immune function in zebrafish.

• Proceedings of the KOSOMBE Conference
• /
• v.1993 no.05
• /
• pp.45-48
• /
• 1993

High-order field gradients are useful for spatial localization of a volume of interest and dynamic range improvement of signal detection in NMR (Nuclear Magnetic Resonance) spectroscopy and imaging. This paper proposes a design method of shielded high-order gradient coils to reduce tile effect of eddy current on tile spectroscopy and imaging results. According to the experimental results, the shielded gradient coils produce less than 2 % eddy current compared to non-shielded coils. Two shielded $z^2$ gradient coils have been designed and constructed for 1.5 T whole-body and 3.0 T animal NMR imaging systems. Experimental results are in good agreement with the theoretically expected behavior and show the utility of the shielded high-order gradient coils.

• Carbon letters
• /
• v.27
• /
• pp.90-97
• /
• 2018

Electromagnetic interference (EMI) shielding is an important issue in modern daily life due to the increasing prevalence of electronic devices and their compact design. This study estimated EMI-shielding effect (EMI-SE) of small ($8-14{\times}17mm$) Hanji (Korean traditional paper) doped with carbon nanotubes (CNTs) and compared to Hanji without CNT using $^2H$ (92.1 MHz) and $^{23}Na$ (158.7 MHz) nuclear magnetic resonance (NMR) peak area data obtained from 1 M NaCl in $D_2O$ samples in capillary tubes that were wrapped in the Hanji samples. The simpler method of using the variation of reflected power and tuning frequency by inserting the sample into an NMR coil was also tested at 242.9, 158.7, and 92.1 MHz. Overall, EMI shielding was relatively more effective at the higher frequencies. Our results validated that NMR methods to be useful to evaluate EMI-SE, particularly for small, flexible shielding materials, and demonstrated that EMI shielding by absorption is dominant in Hanji mixed with CNT.

• Journal of the Korean Magnetic Resonance Society
• /
• v.23 no.1
• /
• pp.6-11
• /
• 2019

Parahydrogen induced hyperpolarization (PHIP) technique is extensively studied to increase the sensitivity of the conventional NMR spectroscopy and recently try to apply this advanced technique into the revolutionary future of the MRI. The other hyperpolarization technique, which is widely utilized, is DNP (Dynamic Nuclear Polarization)-based hyperpolarization one. Despite its great advances in these fields, it contains several drawbacks to overcome: fast relaxation time, expensive equipment is needed, long build-up time is required (several hours), and batch scale material is hyperpolarized. To overcome all those limitations, one can effectively harness the hyperpolarized spin state of parahydrogen. One important step for utilizing the spin state of parahydrogen is doing well-developed experiments of ALTADENA and PASADENA. Based on those concepts, we successfully obtain the hydrogenation signals of ALTADENA and PASADENA from styrene by using benchtop NMR spectrometer. Also those signals were conceptually analyzed and confirmed with different mechanisms. To our best knowledge, those experiments using 1.4T (benchtop NMR) is the first reported one. Considering these experiments, we hope that parahydrogen-based hyperpolarization transfer studies in NMR/MRI will be broadened in Korea in the future.

• Mycobiology
• /
• v.47 no.3
• /
• pp.346-349
• /
• 2019

AMP-activated protein kinase sucrose non-fermenting 1 (Snf1) is a representative regulator of energy status that maintains cellular energy homeostasis. In addition, Snf1 is involved in the mediation of environmental stress such as salt stress. Snf1 regulates metabolic enzymes such as acetyl-CoA carboxylase, indicating a possible role for Snf1 in metabolic regulation. In this article, we performed nuclear magnetic resonance (NMR) spectroscopy to profile the metabolic changes induced by Snf1 under environmental stress. According to our NMR data, we suggest that Snf1 plays a role in regulating cellular concentrations of a variety of metabolites during environmental stress responses.

• Journal of the Korean Magnetic Resonance Society
• /
• v.24 no.3
• /
• pp.86-90
• /
• 2020

Iron-sulfur (Fe-S) clusters are one of the most ancient yet essential cofactors mediating various essential biological processes. In prokaryotes, Fe-S clusters are generated via several distinctive biogenesis mechanisms, among which the ISC (Iron-Sulfur Cluster) mechanism plays a house-keeping role to satisfy cellular needs for Fe-S clusters. The Escherichia coli ISC mechanism is maintained by several essential protein factors, whose structural characterization has been of great interest to reveal mechanistic details of the Fe-S cluster biogenesis mechanisms. In particular, nuclear magnetic resonance (NMR) spectroscopic approaches have contributed much to elucidate dynamic features not only in the structural states of the protein components but also in the interaction between them. The present minireview discusses recent advances in elucidating structural features of IscU, the key player in the E. coli ISC mechanism. IscU accommodates exceptional structural flexibility for its versatile activities, for which NMR spectroscopy was particularly successful. We expect that understanding to the structural diversity of IscU provides critical insight to appreciate functional versatility of the Fe-S cluster biogenesis mechanism.

• Journal of the Korean Magnetic Resonance Society
• /
• v.24 no.3
• /
• pp.91-95
• /
• 2020

Transthyretin (TTR) is an abundant protein in blood plasma and cerebrospinal fluid (CSF), working as a homo-tetrameric complex to transport thyroxine (T₄) and a holo-retinol binding protein. TTR is well-known for its amyloidogenic property; several types of systemic amyloidosis diseases are caused by aggregation of either wild-type TTR or its variants, for which more than 100 mutations were reported to increase the amyloidogenicity of TTR. The rate-limiting step of TTR aggregation is the dissociation of a monomeric subunit from a tetrameric complex. A wide range of biochemical and biophysical techniques have been employed to elucidate the TTR aggregation processes, among which nuclear magnetic resonance (NMR) spectroscopy contributed much to characterize the structural and functional features of TTR during its aggregation processes. The present review focuses on discussing the recent advances of our understanding to the amyloidosis mechanism of TTR and to the structural features of its monomeric aggregation-prone state in solution. We expect that the present review provides novel insights to appreciate the molecular basis of TTR amyloidosis and to develop novel therapeutic strategies to treat diverse TTR-related diseases.

• Journal of the Korean Magnetic Resonance Society
• /
• v.23 no.1
• /
• pp.26-32
• /
• 2019

${\alpha}B$-crystallin (${\alpha}BC$) is a member of a small heat-shock protein (sHSP) superfamily and plays a predominant role in cellular protein homeostasis network by rescuing misfolded proteins from irreversible aggregation. ${\alpha}BC$ assembles into dynamic and polydisperse high molecular weight complexes containing 12 to 48 monomers; this variable stereochemistry of ${\alpha}BC$ has been linked to quaternary subunit exchange and its chaperone activity. The chaperone activity of ${\alpha}BC$ poses great potential as therapeutic agents for various neurodegenerative diseases. In this mini-review, we briefly outline the recent advancement in structural characterization of ${\alpha}BCs$ and its potential role to inhibit protein misfolding and aggregation in various human diseases. In particular, nuclear magnetic resonance (NMR) spectroscopy and its complimentary techniques have contributed much to elucidate highly-dynamic nature of ${\alpha}BCs$, among which notable advancements are discussed in detail. We highlight the importance of resolving the structural details of various ${\alpha}BC$ oligomers, their quaternary dynamics, and structural heterogeneity.

• Journal of the Korean Magnetic Resonance Society
• /
• v.24 no.3
• /
• pp.70-76
• /
• 2020

The CRISPR-Cas system provides an adaptive immunity for bacteria and archaea against invading phages or foreign plasmids. In the type II CRISPR-Cas system, a single effector protein Cas9 and a guide RNA form an RNA-guided endonuclease complex that can degrade DNA targets of foreign origin. To avoid the Cas9-mediated destruction, phages evolved anti-CRISPR (Acr) proteins that neutralize the host bacterial immunity by inactivating the CRISPR-Cas system. Here we report the backbone ¹H, ¹⁵N, and ¹³C resonance assignments of AcrIIA5 that inhibits the endonuclease activity of type II-A Streptococcus thermophilus Cas9 and also Streptococcus pyogenesis Cas9 using triple resonance nuclear magnetic resonance spectroscopy. The backbone chemical shifts of AcrIIA5 predict a disordered region at the N-terminus, followed by an αββββαβββ fold.

• Journal of the Korean Magnetic Resonance Society
• /
• v.17 no.1
• /
• pp.24-29
• /
• 2013

The structural characteristics of 4-coordinate $BO_4$ [B(1)] and 3-coordinate $BO_3$ [B(2)] groups in $BiB_3O_6$ were studied by $^{11}B$ magic angle spinning (MAS) and single-crystal nuclear magnetic resonance (NMR) spectroscopy. The spin-lattice relaxation time in the laboratory frame, $T_1$, for $^{11}B$ decreased slowly with increasing temperature, whereas the spin-lattice relaxation times in the rotating frame, $T_{1{\rho}}$, for B(1) and B(2), which differed from $T_1$, were nearly constant. Further, $T_{1{\rho}}$ for B(1) and B(2) showed very similar trends, although the $T_{1{\rho}}$ value of B(2) was shorter than that of B(1). The 3-coordinate $BO_3$ and 4-coordinate $BO_4$ were distinguished by $^{11}B$ MAS NMR spectrum and $T_{1{\rho}}$.