• Journal of the Korean Magnetic Resonance Society
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• v.24 no.3
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• pp.70-76
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• 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
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• v.15 no.1
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• pp.54-68
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• 2011

$^1H$ nuclear magnetic resonance (NMR) spectroscopy of biological samples has been proven to be an effective and nondestructive approach to probe drug toxicity within an organism. In this study, ketoprofen toxicity was investigated using $^1H$-NMR spectroscopy coupled with multivariate statistical analysis. Histopathologic test of ketoprofen-induced acute gastrointestinal damage in rats demonstrated a significant dose-dependent effect. Furthermore, principal component analysis (PCA) derived from $^1H$-NMR spectra of urinary samples showed clear separation between the vehicle-treated control and ketoprofen-treated groups. Moreover, PCA derived from endogenous metabolite concentrations through targeted profiling revealed a dose-dependent metabolic shift between the vehicle-treated control, low-dose ketoprofen-treated (10 mg/kg body weight), and high-dose ketoprofen-treated (50 mg/kg) groups coinciding with their gastric damage scores after ketoprofen administration. The resultant metabolic profiles demonstrated that the ketoprofen-induced gastric damage exhibited energy metabolism perturbations that increased urinary levels of citrate, cis-aconitate, succinate, and phosphocreatine. In addition, ketoprofen administration induced an enhancement of xenobiotic activity in fatty oxidation, which caused increase levels of N-isovalerylglycine, adipate, phenylacetylglycine, dimethylamine, betaine, hippurate, 3-indoxylsulfate, N,N-dimethylglycine, trimethyl-N-oxide, and glycine. These findings demonstrate that $^1H$-NMR-based urinary metabolic profiling can be used for noninvasive and rapid way to diagnose adverse drug effects and is suitable for explaining the possible biological pathways perturbed by nonsteroidal anti-inflammatory drug toxicity.

• Proceedings of the KSMRM Conference
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• 1999.04a
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• pp.1-9
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• 1999

핵자기 공명(NMR:nuclear magnetic resonance)은 19451건 Bloch, Procell등에 의해 처음으로 실험적으로 입증된 후에 생화학 및 약학 분야에서 분자단위의 물질의 성분, 구조, 대사물질의 역학적 운동 및 상태에 관한 정보를 아는데 유용한 기법으로 사용 되어 왔다. 의학분야에서는 Lauterber등에 의해 자기공명영상볍(Magnetic Resonance Imaging:MRI)으로 개발되어 질병의 진단 및 치료에 많은 공헌을 하게되었다. 해부학적영상 뿐 아니라 분석방법으로 병변 부위 및 인체 기관에서의 각종 대사물질의 정량적인 양과 변화를 알 수 있는 자기공명분광기법(magnetic resonance spectroscopy:MRS)도 활발한 임상적용이 이루어지고 있다. 자기공명영상법의 활발한 임상적 응용 및 새로운 technique이해를 위해서는 물리학적 개념(MR Physics)을 이해하는 것이 매우 중요하다.

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

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 1999.06a
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• pp.21-21
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• 1999

• Journal of the Korean Magnetic Resonance Society
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• v.25 no.3
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• pp.39-44
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• 2021

The CRISPR-Cas system provides adaptive immunity for bacteria and archaea against invading phages and foreign plasmids. In the Class 1 CRISPR-Cas system, multi-subunit Cas proteins assemble with crRNA to bind to DNA targets. To disarm the bacterial defense system, bacteriophages evolved anti-CRISPR (Acr) proteins that actively inhibit the host CRISPR-Cas function. Here we report the backbone resonance assignments of AcrIF7 protein that inhibits the type I-F CRISPR-Cas system of Pseudomonas aeruginosa using triple-resonance nuclear magnetic resonance spectroscopy. We employed various computational methods to predict the structure and binding interface of AcrIF7, and assessed the model with experimental data. AcrIF7 binds to Cas8f protein via flexible loop regions to inhibit target DNA binding, suggesting that conformational heterogeneity is important for the Cas-Acr interaction.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.4
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• pp.91-100
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• 2018

Benzisothiazolinone (BIT) is the preservative that is widely used in industrial and household products. In this study, zebrafish (Danio rerio) was exposed to BIT at different concentrations (control, 0.5 g/L, 1.0 g/L and 2.0 g/L) for 72 hours. The techniques of nuclear magnetic resonance (NMR) spectroscopy were applied to analyze the effects of BIT on zebrafish. The advantages of NMR are the minimal sample preparation and high reproducibility of experimental results. With the multivariate statistical analysis, dimethylamine, N-acetylaspartate, glycine and histidine were identified as an important metabolite in differentiating between the control and BIT-exposed group. This study will improve the understanding the metabolite changes in the zebrafish in response to BIT exposure.

• Carbon letters
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• v.27
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• pp.90-97
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• 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
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• v.24 no.3
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• pp.86-90
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• 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
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• v.24 no.3
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• pp.91-95
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• 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.