• 암석학회지
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• 제10권3호
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• pp.233-245
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• 2001

NMR분광법은 현재 화학에서 빼 놓을 수 없는 아주 중요한 연구방법의 하나지만 또한 지질학의 연구에 있어서도 초전도 자석의 발달과 함께 그 중요성이 부각되고 있다. 지질학에 있어서 NMR의 연구 대상 원소로는 광물의 주 구성 성분이며 여러 가지 구조적 정보를 갖고 있는 $^{29}Si$, $^{27}Al$ 등이 유용하게 사용되며 이들은 각각 다른 여러 정보들을 제공한다. 이 밖에도 $^{23}Na$와 같은 알칼리금속과 더불어 다양한 핵종들이 지질학에서 NMR로 연구되고 있다. NMR을 이용하여 다양한 방면의 연구들이 가능한데 NMR은 XRD, TEM보다도 더욱 작은 미시적인 (분자적 관점에서의) 구조 연구에 사용될 수 있다. 이러한 연구를 통해 Al, Si 질서-무질서, 산소원자와의 배위수, 인근의 다른 양이온의 분포 등을 포함한 구조적 정보를 알 수 있다. 또한 NMR의 또 다른 장점은 정적인 미시 구조뿐만 아니라 분자들의 움직임(dynamics)에 대한 정보도 알 수 있다는 것이다. 이러한 동적인 정보는 기존의 어느 방법으로도 알기 어려웠던 부분이고 NMR을 통하여 분자들의 상호 교환 속도와 활성화 에너지 등에 대한 폭 넓은 이해가 가능할 수 있다. 이 밖에 NMR을 이용하여 비정질 물질에 대한 구조와 더불어 지표면에서 산출되는 유기물에 대한 성분 및 구조도 아주 중요하게 연구될 수 있는 분야이다.

• 한국자기공명학회논문지
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• 제10권1호
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• pp.96-104
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• 2006

The gene coding for APG8a (At4g21980), a protein from Arabidopsis thaliana, is involved in the autophagy process. The protein is an interesting candidate for structure determination by NMR spectroscopy. Toward this end, APG8a has been produced recombinantly in Escherichia coli and typical NMR experiments such as $^{15}N-HSQC$, HNCA, HN(CO)CA, CBCA(CO)NH, HCCH-TOCSY, HNCO were performed. The backbone resonances, HN, N, CA, CB, and C' were sequence-specifically assigned, and the secondary structures including 3 $\alpha$ helices and $4\beta$ strands were deduced based on the assignments. Due to the intrinsic flexibility or the effect of the denaturant, the backbone resonances were not fully observed. Since the structure calculation by NMR data was not possible, the 3-dimensional model was built based on the sequence homology, and compared with the NMR results. The overall structure of the model could explain and complement the NMR derived secondary structures.

• Applied Biological Chemistry
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• 제41권8호
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• pp.572-577
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• 1998

The solution conformation of the human insulin precursor, preproinsulin, is described in terms of NMR spectral data. NMR experiments were performed on preproinsulin, whose structure was compared with the NMR structure of native human insulin. Despite the presence of the C-peptide and/or the signal peptide, secondary structure analyses indicate that the native structures of the A and B chains are well conserved even in preproinsulin. The observed relative robustness of the native structure in precursor forms permits further protein engineering experiments where the C-peptide or N-terminal signal sequence can be altered for the purpose of increasing expression or purification yields when producing recombinant human insulin.

• Journal of Ginseng Research
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• 제22권2호
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• pp.96-101
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• 1998

This paper describes the determination of bulk density and the discrimination of internal structure of red ginseng by nuclear magnetic resonance (NMR). The 102 red ginseng roots were tested for bulk density. The NMR properties measured by NMR parameters such as spin-lattice relaxation time ($T_1$) and spin-spin relaxation time ($T_2$) were determined using the low field proton NMR analyzer. Bulk density of red ginseng root showed a highly negative significant correlation (r=-0.8934) with the value of $T_1$, but a highly positive significant correlation (r=0.7672 and 0.5909) with the value of T21 (short T2) and T22 (long T2), respectively. Multiple regression equation, Y=-0.0069.$T_1$+0.3044.$T_{21}$-0.0156.$T_{22}$-0.6368, using the MNR parameter values of 80 red ginseng roots can effectively predict the bulk density of 22 red ginseng roots with the correlation coefficient of 0.9396 and the standard error of 0.086. The differences in the internal structure of normal and inside white part of red ginseng were easily found by the signal intensity of NMR image based on magnetic properties of proton nucleus.

• 한국자기공명학회논문지
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• 제20권3호
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• pp.95-101
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• 2016

Apolipoprotein B-100 (Apo-B100) is a major component of low density lipoprotein (LDL). Apo B-100 protein has 4,536 amino acid sequence and these amino acids are classified into peptide groups A to G with subsequent 20 amino acids (P1-P302). The peptide groups were act as immunoglobulin (Ig) antigens which oxidized via malondialdehyde (MDA). The mimetic peptide P1 (EEEMLENVSLVCPKDAT RFK) out of D-group peptides carrying the highest value of IgG antigens were selected for structural studies that may provide antigen specificity. Circular Dichroism (CD) spectra were measured for peptide secondary structure in the range of 190-250 nm. Experimental results show that P1 exhibit partial of ${\beta}-sheet$ and random coil structure. Homonuclear (COSY, TOCSY, NOESY) 2D-NMR experiments were carried out for NMR signal assignments and structure determination for P1. On the basis of these completely assigned NMR spectra and distance data, distance geometry (DG) and Molecular dynamics (MD) were carried out to determine the structures of P1. The proposed structure was selected by comparisons between experimental NOE spectra and back calculated 2D NOE results from determined structure showing acceptable agreement. The total Root-Mean-Square-Deviation (RMSD) value of P1 obtained upon superposition of all atoms was in the range $0.33{\AA}$. The solution state P1 has mixed structure of ${\beta}-sheet$ (Glu[1] to Cys[12]) and random coil (Pro[13] to Lys[20]). These NMR results are well consistent with secondary structure from experimental results of circular dichroism. Structural studies based on NMR may contribute to the studies of atherosclerosis and observed conformational characteristics of apo B-100 in LDL using monoclonal antibodies.

• 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).

• 한국자기공명학회논문지
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• 제11권2호
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• pp.73-84
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• 2007

MTH1821 (UniProtKB/TrEMBL ID O27849) is a 96-residue hypothetical protein from the open reading frame of Methanobacterium thermoautotrophicum H one of the target organisms of structural genomics pilot project. Proteins which contain conserved sequence compared with MTH1821 have not been discovered yet and the functional and structural information for MTH1821 is not available. Here, we present the sequence-specific backbone resonance using multidimensional heteronuc1ear NMR spectroscopy and propose the secondary structure using GetSBY software. The backbone resonances of N, HN, $C_{\alpha}$, $C_{\beta}$, CO and $H_{\alpha}$ which are necessary for a prediction of secondary structure by GetSBY were assigned about 98% (557/568). The secondary structure of MTH1821 confirmed that it is comprised of four strand regions and two helical regions. This report will provide a valuable resource for the calculation solution structure of MTH1821 and for the other hypothetical protein that is targeted for structural-based functional discovery.

• 한국자기공명학회논문지
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• 제24권4호
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• pp.136-142
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• 2020

Apolipoprotein B-100 (apo B-100), the main protein component that makes up LDL (Low density lipoprotein), consists of 4,536 amino acids and serves to combine with the LDL receptor. The oxidized LDL peptides by malondialdehyde (MDA) or acetylation in vivo were act as immunoglobulin (Ig) antigens and peptide groups were classified into 7 peptide groups with subsequent 20 amino acids (P1-P302). The biomimetic peptide P99 (KGTYG LSCQR DPNTG RLNGE) out of B-group peptides carrying the highest value of IgM antigens were selected for structural studies that may provide antigen specificity. Circular Dichroism (CD) spectra were measured for peptide secondary structure in the range of 190-260 nm. Experimental results show that P99 has pseudo α-helice and random coil structure. Homonuclear (COSY, TOCSY, NOESY) 2D-NMR experiments were carried out for NMR signal assignments and structure determination for P99. On the basis of these completely assigned NMR spectra and proton distance information, distance geometry (DG) and molecular dynamic (MD) were carried out to determine the structures of P99. The proposed structure was selected by comparisons between experimental NOE spectra and back-calculated 2D NOE results from determined structure showing acceptable agreement. The total Root-Mean-Square-Deviation (RMSD) value of P99 obtained upon superposition of all atoms were in the set range. The solution state P99 has mixed structure of pseudo α-helix and β-turn(Gln[9] to Thr[13]). These NMR results are well consistent with secondary structure from experimental results of circular dichroism. Structural studies based on NMR may contribute to the prevent oxidation studies of atherosclerosis and observed conformational characteristics of apo B-100 in LDL using monoclonal antibodies.

• Bulletin of the Korean Chemical Society
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• 제22권5호
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• pp.507-513
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• 2001

Histones, nuclear proteins that interact with DNA to form nucleosomes, are essential for both the regulation of transcription and the packaging of DNA within chromosomes. The N-terminal domain of histone H4 which contains four acetylation sites at lysines, may play a separate role in chromatin structure from the remainder of the H4 chain. NMR data suggest that H4NTP peptide does have relating disordered structure at physiological pH, however, it has a defined structure at lower pH conditions. The solution structure calculated from NMR data shows a well structured region comprising residues of Val21-Asp24. In addition, our results suggest that the H4NTP prefers an extended backbone conformation at acetylation sites, however, it (especially Lys 12 ) became more defined structures after acetylation for its optimum function.

• 한국자기공명학회논문지
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• 제23권2호
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• pp.56-60
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• 2019

Study on the structure and dynamics of molecules at the atomic level is of great significance for understanding their function and stability as well as roles for various chemico-physical and biological processes. $^{17}O$ NMR spectroscopy has appeared as an elegant technique for investigating of the physicochemical and structural properties of oxygen-containing compounds such as metal organic frameworks and nanosized oxides. This method has drawn much attention as it provides unique insights into the properties of targets based on atomistic information of local oxygen environments which is otherwise difficult to obtain using other methods. In this mini review, we introduce and discuss the recent study and developments of $^{17}O$ NMR techniques which are tailored for the investigation on the structure and dynamics of water and inorganic materials.