• 한국자기공명학회논문지
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• 제26권1호
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• pp.17-20
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• 2022

High-pressure (HP) NMR is a versatile tool to investigate diverse features of proteins. This technique has been particularly powerful to elucidate structural dynamics that only populates sufficiently in a pressurized condition. Amyloidogenic proteins, which are prone to aggregate and form amyloid fibrils, often maintains highly dynamic states in its native or aggregation-prone states, and HP NMR contributed much to advance our understandings of the dynamic behaviors of amyloidogenic proteins and the molecular mechanisms of their aggregation. In this mini review, we therefore summarize recent HP NMR studies on amyloid-beta (Aβ), the representative amyloidogenic intrinsically disordered protein (IDP).

• Neonatal Medicine
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• 제18권2호
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• pp.182-188
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• 2011

목적: 한국에서 최근 신생아사망률(NMR), 영아사망률(IMR)는 주산기, 신생아, 소아과 의료의 발전으로 현저한 개선을 이루었다. 본 연구는 한국에서 최근 5년간 IMR 중에서 NMR가 차지하는 비율을 알아보아, NMR의 개선이 IMR의 감소에 미친 영향을 알아보고자 한다. 방법: 한국 통계청의 출생 자료 및 신생아 및 영아에 관련된 통계와 보고서의 자료를 기초로 하였다. 2005-2009년 간 한국에서 영아사망 중에서 신생아 사망이 차지하는 비율의 변화와 출생 시의 출생체중와 임신나이에 따른 분포별 사망이 영아사망에 차지하는 비율을 조사하였다. 결과: 2005-2009년 간 한국의 총 출생 수는 감소하였으나, 미숙아 수, 저체중출생아(LBWI) 수, 극수제체중출생아(VLBWI) 수는 증가하였다. 연도별 신생아 및 영아 사망 수, NMR, IMR는 감소하였다. 전체 영아사망 중에서 신생아사망이 차지하는 비율은 2005년 57.1%, 2009년 56.3%로 전체적으로 반 이상을 차지하였다. 신생아사망 중에서는 후기 신생아사망 보다는 조기 신생아사망의 비율이 높았다. 연도별로 출생 시 정상체중아, LBWI, VLBWI, 미숙아 사망 수는 감소추세 이었다. 전체 영아사망 중에서 출생 시 정상체중아에서 사망과 출생 시 LBWI 사망의 비는 2005년 42.1:57.9, 2009년 44.2:55.8, 전체 영아사망 중에서 출생 시 만삭아에서 사망과 미숙아 사망의 비는 2005년 42.9:57.1, 2009년 44.6:55.4로 LBWI, 미숙아의 사망이 높았다. 5년간 평균 수치의 출생체중별, 임신나이별 신생아 사망 비율도 관찰하였다. 결론: 한국에서 저출산 시대에 총 출생 수는 감소하고 있지만, 미숙아 LBWI의 빈도는 증가 추세이다. 한국에서 전반적인 연도별 전체 신생아 및 영아사망 수의 감소와 NMR, IMR의 개선과 IMR에서 NMR이 차지하는 비율의 감소 추세 등이 고무적이지만, 아직도 IMR에서 NMR의 비율은 반 정도를 차지하고 있다. 향후 한국에서 IMR의 보다 좋은 개선을 위하여 NMR의 지속적인 감소가 필요할 것으로 사료되며, 이를 위해서 미숙아 LBWI, 이중에서도 고위험 신생아인 VLBWI와 임신나이 32주 미만의 미숙아의 예후를 더욱 향상해야 할 것이다. 본 자료를 향후 신생아 관리의 기초로 활용되기를 기대한다.

• 분석과학
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• 제7권1호
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• pp.91-102
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• 1994

일련의 polypropylene 계통의 공중합체 및 삼중합체 중에서 단량체의 조성에 관한 조성비를 $^{13}C-NMR$ 스펙트럼을 이용하여 정량하였다. 고온에서 얻어진 고분자의 $^{13}C-NMR$ 스펙트럼은 아주 높은 분해능을 보이며, 이는 모든 시그날을 명확하게 지정하는 것을 가능하게 하였으며, 또한 단량체의 조성비를 계산할 수 있도록 하였다. 따라서 단량체의 조성비를 계산하는 방법을 새롭게 제시하였으며, 고분자에서 dyad, triad, tetrad 및 pentad의 조성비도 계산할 수 있다는 것을 보여 주었다. 이러한 단량체 조성에 관한 NMR 분석 결과는 표준 물질을 이용하여 정량한 IR data와 잘 일치한다는 것을 보여 준다.

• 농약과학회지
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• 제8권2호
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• pp.88-94
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• 2004

농약제품 중 개별부자재의 확인을 위한 분석도구로서 NMR 분광기를 사용하였고 부자재의 표준품 및 농약제품을 분석 비교하였다. 고분자물질인 계면활성제는 co-polymer였고 많은 ethylene 그룹으로 이루어졌다. 가장 두드러진 signal은 긴 체인의 polyoxyethylene 그룹으로 70.5 ppm에서 나타났고 Ester의 carbnyl 그룹은 173.5 ppm에서 자기공명 signal을 확인할 수 있었다. 분석 시료는 정제, 농축, 또는 크로마토그래피의 과정 없이 준비되었고 개별부자재의 확인은 분석된 시료와 표준품 스펙트럼과의 비교에 의하여 가능할 수 있었다. NMR 분광기는 전처리과정 없이 농약제품 중 개별부자재의 분석이 가능하였다.

• Bulletin of the Korean Chemical Society
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• 제7권3호
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• pp.170-178
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• 1986

The NMR chemical shift arising from 4d electron angular momentum and 4d electron angular momentum and 4d electron spin dipolar-nuclear spin angular momentum interactions for a $4d^1$ system in a strong crystal field environment of trigonal symmetry, when the threefold axis is chosen to be the axis of quantization axis, has been examined. A general expression using the nonmultipole expansion method (exact method) is derived for the NMR chemical shift. From this expression all the multipolar terms are determined. We observe that along the (100), (010), (110), and (111) axes the NMR chemical shifts are positive while along the (001) axis, it is negative. We observe that the dipolar term (1/R3) is the dominant contribution to the NMR chemical shift except for along the (111) axis. A comparison of the multipolar terms with the exact values shows also that the multipolar results are exactly in agreement with the exact values around $R{\geqslant}0.2$ nm. The temperature dependence analysis on the NMR chemical shifts may imply that along the (111) axis the contribution to the NMR chemical shift is dominantly pseudo contact interaction. Separation of the contributions of the Fermi and the pseudo contact interactions would correctly imply that the dipolar interaction is the dominant contribution to the NMR chemical shifts along the (100), (010), (001), and (110) axes, but along the (111) axis the Fermi contact interaction is incorrectly the dominant contribution to the NMR chemical shift.

• Bulletin of the Korean Chemical Society
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• 제25권4호
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• pp.529-532
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• 2004

Cesium-133 NMR spectra of a single crystal of tetragonal $Cs^+ (15-crown-5)_2I^-$ were obtained as a function of crystal orientation in an applied magnetic field of 9.40T and analyzed to provide the magnitudes and orientations of the $^{133}Cs$ chemical shift and quadrupolar tensors for two magnetically nonequivalent and symmetry related sites. Chemical shift tensor components and parameters of quadrupolar interactions are obtained as ${\delta}_{11}=46(1),\;{\delta}_{22}=60(1),\;{\delta}_{33}=-30(1)$ ppm, quadrupole coupling constant QCC = 581(1) kHz, and asymmetry parameter ${\eta}$ = 0.481(1), respectively. The nonaxially symmetric NMR parameters imply that the local environment of the cesium nuclei is nonaxially symmetric. The DANTE experiment burned holes in the $^{133}Cs$ NMR line of the title compound. The hole burning of the single crystal and powder $^{133}Cs$ NMR lines showed that the NMR lines are not homogeneously broadened.

• 한국자기공명학회논문지
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• 제19권2호
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• pp.83-87
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• 2015

Syndesmos, which is co-localized with syndecan-4 cytoplasmic domain ($Syn4^{cyto}$) in focal contacts, interacts with various cell adhesion adaptor proteins including $Syn4^{cyto}$ to control cell signaling. Syndesmos consists of 211 amino acids and it exists as a dimer (44kDa) in solution. Recently, we have determined the structure of syndesmos by x-ray crystallography, however, dynamics related to syndecan binding still remain elusive. In this report, we performed NMR experiments to acquire biochemical and structural information of syndesmos. Based on a series of three-dimensional triple resonance experiments on a $^{13}C/^{15}N/^2H$ labeled protein, NMR spectra were obtained with well dispersed and homogeneous NMR data. We present the sequence specific backbone assignment of syndesmos and assigned NMR data with combination structural information can be directly used for the studies on interaction with $Syn4^{cyto}$ and other binding molecules.

• 한국자기공명학회논문지
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• 제18권1호
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• pp.24-29
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• 2014

Atomistic molecular dynamics (MD) simulation has become mature enabling close approximation of the real behaviors of biomolecules. In biomolecular NMR field, atomistic MD simulation coupled with generalized implicit solvent model (GBIS) has contributed to improving the qualities of NMR structures in the refinement stage with experimental restraints. Here all-atom force fields play important roles in defining the optimal positions between atoms and angles, resulting in more precise and accurate structures. Despite successful applications in refining NMR structure, however, the research that has studied the influence of force fields in GBIS is limited. In this study, we compared the qualities of NMR structures of two model proteins, ubiquitin and GB1, under a series of AMBER force fields-ff99SB, ff99SB-ILDN, ff99SB-NMR, ff12SB, and ff13-with experimental restraints. The root mean square deviations of backbone atoms and packing scores that reflect the apparent structural qualities were almost indistinguishable except ff13. Qualitative comparison of parameters, however, indicates that ff99SB-ILDN is more recommendable, at least in the cases of ubiquitin and GB1.

• Journal of Pharmaceutical Investigation
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• 제39권1호
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• pp.43-49
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• 2009

Aspirin or acetylsalicylic acid, a member of the salicylate family, is frequently used as an analgesic, antipyretic, anti-inflammatory and antiplatelet drug. Because aspirin is chemically unstable in water and heat for tablet formulation, additives including lubricants are used in preparing aspirin tablets, using a dry-granulation process. Aspirin tablets are produced by a number of manufacturers which usually use their own unique combination of additives during the manufacturing process. In this study, we employed an NMR based metabolomics technique to identify the manufacturers of various aspirin tablets. Aspirin tablets from six different companies were analyzed by 1H 400 MHz NMR. The acquired data was then integrated and processed by principal component analysis (PCA). Based on the NMR data, we were able to identify peaks corresponding to acetylsalicylic acid in all of the six samples, whereas different NMR patterns were found in the aromatic and aliphatic regions depending on the unique additive used. These observations led to the conclusion that the differences in the NMR patterns among the different aspirin tablets were due to the presence of additives.

• 한국자기공명학회논문지
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• 제3권1호
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• pp.44-51
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• 1999

An enzyme derived conformational changes of cobalamine is thought to be important in the homolytic cleavage of Co-C bond which is the first step of catalytic Cl-cycle of coenzyme B12-dependent enzymes. Modern 2D-NMR and NMR-based distance geometric studies were carried out to determine the 3D structure of corrin ring. Homonuclear and heteronuclear correlation NMR experiments were performed for complete 1H-NMR signal assignments. Distances between numerous proton pairs were deduced based on the NOE cross peak intensities and subsequently used as input into the distance geometry program for the 3D structure determination. The detailed 3D structure from the present NMR-based analysis was compared with the result from X-ray crystallographic study, which revealed greater conformational changes occur in benzimidazole group and sugar ring than in macrocyclic corrin and tetrapyrrole. In addition, the distance geometry used in this study was found to be quite useful for NMR-based structure determination of medium-sized molecules that give poor NOE effects arising from their intermediate tumbling rate ($\omega$$\tau$c 1.0).