• Journal of Ginseng Research
• /
• 제38권2호
• /
• pp.116-122
• /
• 2014

Ginseng roots were extracted with aqueous methanol, and extracts were suspended in water and extracted successively with ethyl acetate and n-butanol. Column chromatography using the n-butanol fraction yielded four purified triol ginseng saponins: the ginsenosides Re, Rf, Rg2, and 20-gluco-Rf. The physicochemical, spectroscopic, and chromatographic characteristics of the ginsenosides were measured and compared with reports from the literature. For spectroscopic analysis, two-dimensional nuclear magnetic resonance (NMR) methods such as $^1H$-$^1H$ correlation spectroscopy, nuclear Overhauser effect spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond connectivity were employed to identify exact peak assignments. Some peak assignments for previously published $^1H$-and $^{13}C$-NMR spectra were found to be inaccurate. This study reports the complete NMR assignment of 20-gluco-Rf for the first time.

• Bulletin of the Korean Chemical Society
• /
• 제30권11호
• /
• pp.2535-2541
• /
• 2009

Prebiotic isomaltooligosaccharide preparations contain $\alpha$-D-glucooligosaccharides comprising isomaltooligosaccharides (IMOs) and non-prebiotic maltooligosaccharides (MOs). They are both glucose oligosaccharides characterized by their degree of polymerization (DP) value (from 2 to $\sim$10), linkages types and positions (IMOs: $\alpha$-(1$\rightarrow$2, 3, 6 and in a lower proportion internal 1$\rightarrow$4) linkages, MOs: α-(1$\rightarrow$4) linkages). Their structure is the key factor for their prebiotic potential. In order to determine and elucidate the exact structure of unknown IMOs and MOs, unambiguous assignments of $^{13}C$ and $^1H$ chemical shifts of commercial standards, representative of IMOs and MOs diversity, have been determined using optimized standard one and two-dimensional experiments such as $^1H$ NMR, $^{13}C$ NMR, APT and ${^1}H-{^1}H$ COSY, TOCSY, NOESY and <$^1H-{^{13}}C$ heteronuclear HSQC, HSQC-TOCSY, and HMBC. Here we point out the differential effect of substitution by a glucose residue at different positions on chemical shifts of anomeric as well as ring carbons together with the effect of the reducing end configuration for low DP oligosaccharides and diasteroisotopic effect for H-6 protons. From this study, structural $^{13}C$ specific spectral features can be identified as tools for structural analysis of isomaltooligosaccharides.

• 한국자기공명학회논문지
• /
• 제20권2호
• /
• pp.56-60
• /
• 2016

Adenylate kinase (AK) enzyme which acts as the catalyst of reversible high energy phosphorylation reaction between ATP and AMP which associate with energetic metabolism and nucleic acid synthesis and signal transmission. This enzyme has three distinct domains: Core, AMP binding domain (AMPbd) and Lid domain (LID). The primary role of AMPbd and LID is associated with conformational changes due to flexibility of two domains. Three dimensional structure of human AK1 has not been confirmed and various mutation experiments have been done to determine the active sites. In this study, AK1R138A which is changed arginine[138] of LID domain with alanine[138] was made and conducted with NMR experiments, backbone dynamics analysis and mo-lecular docking dynamic simulation to find the cause of structural change and substrate binding site. Synthetic human muscle type adenylate kinase 1 (hAK1) and its mutant (AK1R138A) were re-combinded with E. coli and expressed in M9 cell. Expressed proteins were purified and finally gained at 0.520 mM hAK1 and 0.252 mM AK1R138A. Multinuclear multidimensional NMR experiments including HNCA, HN(CO)CA, were conducted for amino acid sequence analysis and signal assignments of $^1H-^{15}N$ HSQC spectrum. Our chemical shift perturbation data is shown LID domain residues and around alanine[138] and per-turbation value(0.22ppm) of valine[179] is consid-ered as inter-communication effect with LID domain and the structural change between hAK1 and AK1R138A.

• Natural Product Sciences
• /
• 제14권2호
• /
• pp.90-94
• /
• 2008

Two sesquiterpenes (1 - 2), a tetralone (3), and two phenylpropanoids (4 - 5) were isolated from the stem bark of Magnolia obovata Thunberg (Magnoliaceae) through repeated column chromatography. Their structures were identified as ${\beta}-eudesmol$ (1), cryptomeridiol (2), 4R-4,8-dihydroxy-${\beta}-tetralone$ (3), trans-pcoumaryl aldehyde (4), and p-coumaric acid (5) on the basis of spectroscopic analysis including two dimensional NMR and mass. Compounds 1 - 3 were tested in vitro for their cytotoxic activity against the K562, HeLa, A549, and HCT116 cancer cell lines. However, compounds 1 - 3 were inactive in this assay system.

• Bulletin of the Korean Chemical Society
• /
• 제14권1호
• /
• pp.137-143
• /
• 1993

The tetranuclear heterometallic complex CpMo$Os_3(CO)_{10}({\mu]-H)2[{\mu}3-{\eta}^2-C(O)CH_2Tol]\;(1,\;Cp={\eta}^5-C_5H_5,\;Tol=p-C_6H_4Me)$ has been examined by variable-temperature $^{13}$C-NMR spectroscopy and by a full three-dimensional X-ray structual analysis. Complex 1 crystallizes in the orthorhombic space group Pna2$_1$ with a = 12.960(1) ${\AA}$, b = 11.255(l) ${\AA}$, c = 38.569(10)${\AA}$, V = 5626(2) ${\AA}^3$ and ${\rho}$(calcd) = 2.71 gcm$^{-3}$ for Z = 8 and molecular weight 1146.9. Diffraction data were collectedon a CAD4 diffractometer, and the structure was refined to $R_F$ = 9.7% and $R_{W^F}$ = 9.9% for 2530 data (MoK${\alpha}$ radiation). There are two essentially equivalent molecules in the crystallographic asymmetric unit. The tetranuclear molecule contains a triangulated rhomboidal arrangement of metal atoms with Os(2) and Mo at the two bridgehead positions. The metal framework is planar; the dihedral angle between Os(l)-Os(2)-Mo and Os(3)-Os(2)-Mo planes is 180$^{\circ}$. A triply bridging (${\mu}_3,\;{\eta}^2$) acyl ligand lies above the Os(l)-Os(2)-Mo plane; the oxygen atom spans the two bridgehead positions, while the carbon atom spans one bridgehead position and an acute apical position. The molecular architecture is completed by an ${\eta}^5$-cyclopentadienyl ligand and a semi-triply bridging carbonyl ligand on the molybdenum atom, and nine terminal carbonyl ligands-four on Os(3), three on Os(l), and two on Os(2). The two hydride ligands are inferred to occupy the Os(l)-Os(2) and Mo-Os(3) edges from structural and NMR data.

• 한국자기공명학회논문지
• /
• 제3권1호
• /
• pp.60-70
• /
• 1999

The pyrimidine(6-4) pyrimidone photoproduct [(6-4) adduct] is one of the major photoproducts induced by UV irradiation of DNA and occurs at TpT sites. The (6-4) adduct is highly mutagenic and specific during translesion replication. The marked preference for insertion of A opposite the 5'-T and G opposite the 3--T of the (6-4) adducts leads to a predominantly 3'-T\longrightarrowC transition with 85% replicating error rate. In order to obtain insight into the origin of 3'-T\longrightarrowC transition induced by the (6-4) adduct, we have performed one - and two-dimensional NMR experiment. The 3'-Tof the (6-4) lesion forms the stable hydrogen bonding to the imino proton of an opposed G, which stabilizes the overall helix and diminishes the highly distorted conformation caused by the (6-4) lesion in the (6-4)/AA duplex. We proposed that the greater insertion of a G over an A opposite the 3'-T of the (6-4) lesion These results may account for the greater preference for the insertion of a G over a A opposite the 3'-T of the (6-4) lesion. Thus this insertion leads to the highly specific 3'-T\longrightarrowC multation at the (6-4) lesion site.

• BMB Reports
• /
• 제31권1호
• /
• pp.48-52
• /
• 1998

$p16^{INK4}$, which is a 16-kDa polypeptide protein, inhibits the catalytic activity of the CDK4-cyclinD complex to suppress rumor growth. Both unlabeled and isotope-labeled human tumor suppressor $p16^{INK4}$ protein were overexpressed and purified to characterize biochemical and structural properties. The purified p16 binds to monomeric GST-CDK4 and exists in a monomer conformation for several weeks at $4^{\circ}C$. The circular dichroism (CD) data indicates that p16 contains high percentage of ${\alpha}$-helix and that the helix percentage maximized at pH value of 7.0. One-and two-dimensional nuclear magnetic resonance (NMR) data suggest that purified p16 from our construct has a unique folded conformation under our experimental conditions and exhibits quite stable conformational characteristics.

• Journal of Microbiology and Biotechnology
• /
• 제10권6호
• /
• pp.889-892
• /
• 2000

Antisense molecules are structurally simple linear oligomers of nucleotides. They can recognize a complementary sequence by base pairing, therefore, antisense drugs composed of 15-16 bases are potentially useful, unlike drugs such as protein agonists, antagonists, and inhibitors. Since antisense oligomers are classified as nucleotides, they are subject to attack by nucleases. In order to be antisense drugs resistant to degradation by nucleases, the structural modifications in the linkages, bases, and sugars to satisfy this requirement are considerable. We attempted in this study, to synthesize 16-mer antisenses with a modified linkage and adenosine. When studying on the three-dimensional structure of the oligomer, however, the existence of isomers may complicate the interpretation of the NMR data. Therefore, an attempt was made to eliminate the above problem, thus, two dimers were synthesized and their structural studies were carried out.

• Bulletin of the Korean Chemical Society
• /
• 제33권12호
• /
• pp.4041-4046
• /
• 2012

The recombinant expression of proteins has been the method of choice to meet the demands from proteomics and structural genomics studies. Despite its successful production of many heterologous proteins, Escherichia coli failed to produce many other proteins in their native forms. This may be related to the fact that the stresses resulting from the overproduction interfere with cellular processes. To better understand the physiological change during the overproduction phase, we profiled the metabolites along the time course of the recombinant protein expression. We identified 32 metabolites collected from different time points in the protein production phase. The stress induced by protein production can be characterized by (A) the increased usage of aspartic acid, choline, glycerol, and N-acetyllysine; and (B) the accumulation of adenosine, alanine, oxidized glutathione, glycine, N-acetylputrescine, and uracil. We envision that this work can be used to create a strategy for the production of usable proteins in large quantities.

• Bulletin of the Korean Chemical Society
• /
• 제20권3호
• /
• pp.301-306
• /
• 1999

Hepatitis C virus (HCV) has been known to be an enveloped virus with a positive strand RNA genome and the major agent of the vast majority of transfusion associated cases of hepatitis. For viral replication, HCV structural proteins are first processed by host cell signal peptidases and NS2/NS3 site of the nonstructural protein is cleaved by a zinc-dependent protease NS2 with N-terminal NS3. The four remaining junctions are cleaved by a separate NS3 protease. The solution conformations of NS4B/5A, NS5A/5B substrates and NS5A/5B inhibitor have been determined by two-dimensional nuclear magnetic resonance (NMR) spectroscopy. NMR data suggested that the both NS5A/5B substrate and inhibitor appeared to have a folded tum-like conformation not only between P1 and P6 position but also C-terminal region, whereas the NS4B/5A substrate exhibited mostly extended conformation. In addition, we have found that the conformation of the NS5A/5B inhibitor slightly differs from that of NS5A/5B substrate peptide, suggesting different binding mode for NS3 protease. These findings will be of importance for designing efficient inhibitor to suppress HCV processing.