共查询到20条相似文献,搜索用时 15 毫秒
1.
T Sakaki M Inoue S Senda K Tomita 《Biochemical and biophysical research communications》1978,83(1):21-26
The crystal and molecular structure of the title complex has been determined by X-ray diffraction methods. The crystals contain one water molecule per asymmetric unit, which plays a important role in the molecular packing by forming hydrogen bonds with two carboxyl oxygen atoms of indole-3-acetic acid and a carbamoyl nitrogen atom of the 1-methyl-3-carbamoylpyridinium cation. Prominent stacking between the indole ring and the pyridinium ring, caused by the πD?πA interaction, is observed. This overlap with substantial result may provide a model for the stacking interaction between NAD+ and the tryptophanyl residues in the proteins. 相似文献
2.
Masatoshi Inoue Hiroshi Hirano Kazuaki Sugiyama Toshimasa Ishida Masayuki Nakagaki 《Biochemical and biophysical research communications》1982,108(2):604-609
The crystal structure of thiamin indole-3-propionate was determined by X-ray diffraction as a model for the possible thiamin coenzyme-tryptophan residue interaction at the binding site of thiamin pyrophosphate dependent enzymes. There is an intermolecular stacking interaction of the indole ring with the pyrimidine ring, but not with the positively charged thiazolium ring, of thiamin retaining the characteristic F-conformation. Although this association is due to dipole-dipole interaction between both aromatic rings, charge-transfer interaction cannot be ruled out in solution state because the absorption spectrum shows the characteristic charge-transfer band. 相似文献
3.
The interaction between 1-decyloxymethyl-3-carbamoylpyridinium salts (PS-X) and two types of vesicles (multilamellar vesicle and sonicated vesicle) was investigated. Vesicles were formed from two classes of phospholipids: 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphatidylethanolamine (DPPE). The PS-X salts used had nitrate, perchlorate, tetrafluoroborate and halides as counterions. Measurements were carried out using differential scanning calorimetry and 1H NMR. All studied compounds decreased the main phase transition temperatures of both DPPC and DPPE bilayers. All of them also decreased the transition enthalpy of DPPC bilayers, however they had a dual effect on the transition enthalpy of DPPE. Namely, at low concentrations the PS-X salts studied significantly increased the main transition enthalpy of DPPE (perchlorate and tetrafluoroborate the least among them) and decreased it at higher concentrations. We have suggested that surfactant rich and pure domains form on the DPPE bilayer in the presence of PS-ClO4, PS-BF4 and PS-NO3, whereas they form on DPPC bilayer only in the presence of PS-ClO4. Results are discussed in terms of counterion molecular geometry and the ability of amide group to form hydrogen bonds with lipids. 相似文献
4.
Kraft M Kuglitsch R Kwiatkowski J Frank M Grossmann K 《Journal of experimental botany》2007,58(6):1497-1503
5.
The crystal structure of chloro-(1-methyltyminato- N3)-cis-diammineplatinum(II) monohydrate, cis- (NH3)2Pt(C6H7N2O2)Cl·H2O, is reported. The compound crystallizes in space group P with a = 6.911(2) Å, b = 8.598(3) Å, c = 11.464(4) Å, α = 100.13(3)°, β = 120.03(3)°, γ = 93.16(3)°, Z = 2. The structure was refined to R = 0.048 and Rw = 0.057. The compound contains the deprotonated 1-methylthymine ligand coordinated to Pt through N3 (1.973(10) Å). This distance represents the shortest Pt-N3(pyrimidine-2.4-dione) bond reported so far. The two PtNH3 bond lengths differ significantly: PtNH3 (trans to Cl) is longer (2.052(10) Å) than PtNH3 (trans to N3 of 1-MeT) (2.002(11) Å). The PtCl distance (2.326(3) Å) is normal, as is the large dihedral angle between the Pt coordination plane and the nucleobase (76.5°). 相似文献
6.
Thiago Gumiere Carlos Marcelo Ribeiro Rafael Leandro Figueiredo Vasconcellos Elke Jurandy Bran Nogueira Cardoso 《Antonie van Leeuwenhoek》2014,105(4):663-669
Araucaria forests in Brazil today correspond to only 0.7 % of the original 200 km2 of natural forest that covered a great part of the southern and southeastern area of the Atlantic Forest and, although Araucaria angustifolia is an endangered species, illegal exploitation is still going on. As an alternative to the use of hardwoods, Pinus elliottii presents rapid growth and high tolerance to climatic stress and low soil fertility or degraded areas. Thus, the objective of this study was to evaluate the effect of IAA-producing bacteria on the development of A. angustifolia and P. elliottii. We used five bacterial strains previously isolated from the rhizosphere of A. angustifolia, which produce quantities of IAA ranging from 3 to 126 μg mL?1. Microbiolized seeds were sown in a new gnotobiotic system developed for this work, that allowed the quantification of the plant hormone IAA produced by bacteria, and the evaluation of its effect on seedling development. Also, it was shown that P. elliottii roots were almost as satisfactory as hosts for these IAA producers as A. angustifolia, while different magnitudes of mass increases were found for each species. Thus, we suggest that these microbial groups can be helpful for the development and reestablishment of already degraded forests and that PGPR isolated from Araucaria rhizosphere have the potential to be beneficial in seedling production of P. elliottii. Another finding is that our newly developed gnotobiotic system is highly satisfactory for the evaluation of this effect. 相似文献
7.
8.
Christopher W GlynnMark M Turnbull 《Inorganica chimica acta》2002,332(1):92-100
2,6-Bis(1-triazolo)pyridine (1) was synthesized and characterized via IR and NMR. The regiochemistry of the compound was confirmed via single crystal X-ray analysis of the hydrochloride salt. A series of insoluble complexes of the general formulae M(1)2(X)2 or M(1)(X)2 [M=Co(II), Ni(II), Cu(II); X=ClO4, BF4, Cl] were prepared and their structures interpreted in light of infrared spectra and composition analysis. The results suggest that first row transition metals are not chelated by 1, but rather form extended coordination polymeric networks. A second family of complexes was prepared using 2,6-bis(1-imidazolo)pyridine to support this interpretation. 相似文献
9.
10.
The three-dimensional structure of 3-(adenin-9-yl)propionhistamide hydrochloride, as a model of interactions between the protonated imidazolyl group and adenine moiety, has been determined by X-ray crystallography. The crystal data are a = 10.314 (1), b = 7.854 (1), c = 20.780 (1) A, beta = 92.765 (4), Z = 4, Dm = 1.32 g X cm-3, space group P2(1)/n. The imidazolium group interacts with adenine moiety by stacking. A comparison with the related neutral derivatives leads to a hypothesis that adenine stacks with the protonated, but not with the neutral, imidazolyl group. Such a characteristic behaviour of the imidazolyl group depending on protonation was shown by ultraviolet and NMR spectroscopy, and by polarographic experiments in solution. We note that a role of the essential histidine in RNAase reaction is a switch between capture and ejection of the substrate, which depends upon proton uptake and its release, respectively. 相似文献
11.
Pseudomonas fluorescens strain CHA0 is an effective biocontrol agent against soil-borne fungal plant pathogens. In this study, indole-3-acetic acid (IAA) biosynthesis in strain CHA0 was investigated. Two key enzyme activities were found to be involved: tryptophan side chain oxidase (TSO) and tryptophan transaminase. TSO was induced in the stationary growth phase. By fractionation of a cell extract of strain CHA0 on DEAE-Sepharose, two distinct peaks of constitutive tryptophan transaminase activity were detected. A pathway leading from tryptophan to IAA via indole-3-acetamide, which occurs in Pseudomonas syringae subsp. savastanoi, was not present in strain CHA0. IAA synthesis accounted for less than or equal to 1.5% of exogenous tryptophan consumed by resting cells of strain CHA0, indicating that the bulk of tryptophan was catabolized via yet another pathway involving anthranilic acid as an intermediate. Strain CHA750, a mutant lacking TSO activity, was obtained after Tn5 mutagenesis of strain CHA0. In liquid cultures (pH 6.8) supplemented with 10 mM-L-tryptophan, growing cells of strains CHA0 and CHA750 synthesized the same amount of IAA, presumably using the tryptophan transaminase pathway. In contrast, resting cells of strain CHA750 produced five times less IAA in a buffer (pH 6.0) containing 1 mM-L-tryptophan than did resting cells of the wild-type, illustrating the major contribution of TSO to IAA synthesis under these conditions. In artificial soils at pH approximately 7 or pH approximately 6, both strains had similar abilities to suppress take-all disease of wheat or black root rot of tobacco. This suggests that TSO-dependent IAA synthesis is not essential for disease suppression. 相似文献
12.
We describe herein the high resolution refined x-ray structure of a trisaccharide, which is a part of the N-acetyllactosamine type glycan found in the majority of the N-glycosyl-proteins, complexed to the isolectin I. According to the potentials used by Imberty et al. (Imburty, A., Gerber, S., Tran, V., and Pérez, S. (1990) Glycoconjugate J. 7, 27-54) the trisaccharide is in a low-energy state. Only one mannose moiety establishes direct hydrogen bonds with the lectin, as it is the case for monosaccharide-lectin complexes. The comparison of our trisaccharide with the one determined in solution by Warin et al. (Warin, V., Baert, F., Fouret, R., Strecker, G., Fournet, B., and Montreuil, J. (1979) Carbohydr. Res. 76, 11-22) shows that both adopt roughly the same conformation. The differences in these two sugar structures allow us to assign the role of water molecules present in the vicinity of our trisaccharide for the stabilization of this sugar-lectin complex. 相似文献
13.
The crystal structures of the 2:1 complex of the self-complementary DNA octamer d(GAAGCTTC) with actinomycin D has been determined at 3.0 A resolution. This is the first example of a crystal structure of a DNA-drug complex in which the drug intercalates into the middle of a relatively long DNA segment. The results finally confirmed the DNA-actinomycin intercalation model proposed by Sobell & co-workers in 1971. The DNA molecule adopts a severely distorted and slightly kinked B-DNA-like structure with an actinomycin D molecule intercalated in the middle sequence, GC. The two cyclic depsipeptides, which differ from each other in overall conformation, lie in the minor groove. The complex is further stabilized by forming base-peptide and chromophore-backbone hydrogen bonds. The DNA helix appears to be unwound by rotating one of the base-pairs at the intercalation site. This single base-pair unwinding motion generates a unique asymmetrically wound helix at the binding site of the drug, i.e. the helix is loosened at one end of the intercalation site and tightened at the other end. The large unwinding of the DNA by the drug intercalation is absorbed mostly in a few residues adjacent to the intercalation site. The asymmetrical twist of the DNA helix, the overall conformation of the two cyclic depsipeptides and their interaction mode with DNA are correlated to each other and rationally explained. 相似文献
14.
Karasev VA Fundamensky VS Bannova II Franke VD Stefanov VE 《Biochimica et biophysica acta》2000,1466(1-2):23-38
A crystal complex consisting of the isobutyl analog of phosphatidylcholine (PC) (isobutylphosphocholine), cholesterol, and isobutanol with molecular ratio 1:3:3 was obtained and investigated by means of X-ray analysis. The complex was shown to correspond to the monoclinic system (sp. gr. P2(1)): a=16.994(10), b=11.314(7), c=28.164(15), beta=104.07(3), V=5252.63 A(3), Z=2, D(calc)=1.0273 g/cm(3). The isobutylphosphocholine molecule is the key component of the complex. Pairs of hydrogen bonds are formed between the (-delta)O-P-O(delta-) group of the isobutylphosphocholine molecule and C-OH groups of two cholesterol and two isobutanol molecules. The third molecules of cholesterol and isobutanol are H-bonded with the (-delta)O-P-O(delta-) group of the isobutylphosphocholine molecule via C-OH groups of isobutanol and cholesterol, respectively. The crystal structure is built up by translation of the complex in multiplicate along the two-fold axis in the direction of axis b. It contains bands formed by isobutylphosphocholine molecules alternately changing their direction. They are fixed by virtue of two zones of electrostatic interactions of the type (-delta)O-P-O(delta-)ellipsis(+)N(CH(3))(3) and are more or less parallel to the bc plane. The structure also contains three-layer domains formed by cholesterol molecules perpendicular to isobutylphosphocholine bands. In the direction of the c-axis isobutylphosphocholine bands alternate with the layers of cholesterol molecules herewith reproducing repeated blocks. The obtained structure is compared with that of crystals of phospholipids and cholesterol and its derivatives. 相似文献
15.
16.
The crystal structure of cyclo(Pro-Gly)3 (PG3) complex with LiSCN (C22H30N7O6SLi) has been solved by x-ray diffraction. The crystals belong to the space group R3 in the hexagonal setting with unit cell parameters of a = 12.581(1), c = 29.705(3) Å, V = 4072.0 Å3, Z = 6, Mr = 527.53, Dc = 1.23 g/cm3. The crystal structure was solved by direct methods using the program SHELXS-86 and refined to an R value of 5.3% for 1645 reflections (I > 2σI). There are two conformers in the crystal structure. One conformer has three carbonyls on one side and three on the other side of the peptide plane. The other conformer has all six of the carbonyls on the same side of the peptide plane. Both of these conformers bind independently to a Li ion. Based on the conformers of the Li complex and other reported ion complexes formed by PG3, we propose a model for the transport of ions across the lipid membrane. The features of the model are as follows: (1) PG3 forms a hexameric stack in a lipid bilayer when complexing and transporting metal ions. (2) It undergoes a conformational flipping in order pass the ion along the channel. The energy required for the conformational change involved in the flipping of the PG3 molecule may be provided by the applied potential during ion transport. © 1994 John Wiley & Sons, Inc. 相似文献
17.
The structure of the carboxypeptidase A complex with the inhibitor (S)-(+)-1-amino-2-phenylethylphosphonic acid has been determined at 0.23 nm resolution. The delta F map shows electron-density peaks both in the S1 and S'1 sites, where the inhibitor molecule can be modeled in two different orientations with approximate 50% occupancy. In the proposed model, the phosphonate group binds to the zinc ion in a monodentate fashion. Other anchoring groups for the inhibitor molecule are Arg127 (hydrogen bonds with the phosphonate oxygen atoms) and Glu270 (hydrogen bond with the amino group in one of the two orientations). A recent spectroscopic investigation of the complex between cobalt(II) carboxypeptidase A and (S)-(+)-1-amino-2-phenylethylphosphonic acid is essentially in agreement with our results. 相似文献
18.
C C Tsai S C Jain H M Sobell 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1975,272(915):137-146
The intercalative trypanosomal drug, ethidium bromide, forms a crystalline complex with the dinucleoside monophosphate, 5-iodiuridylyl(3'-5')adenosine (iodoUpA). These crystals are monoclinic, space group C2, with unit cell dimensions, a = 2.845 nm, b = 1.354 nm, c = 3.413 nm, beta = 98.6 degrees. The structure has been solved to atomic resolution by Patterson and Fourier methods, and refined by full matrix least squares to a residual of 0.29 on 2017 observed reflexions. The asymmetric unit contains two ethidium molecules, two iodoUpA molecules, twenty water molecules and four methanol molecules, a total of 156 atims excluding hydrogens. The two iodoUpA molecules are held together by adenine-uracil Watson-Crick base-pairing. Adjacent base-pairs within this paired iodoUpA structure and between neighbouring iodoUpA molecules in adjoining unit cells are separated by 0.68 nm. This separation results from intercalative binding by one ethidium molecule and stacking by the other symmetry is utilized in this model drub-nucleic acid interaction, the intercalative ethidium molecule being oriented such that its phenyl and ethyl groups lie in the narrow groove of the miniature nucleic acid double helix. Solution studies have indicated a marked sequence specificity for ethidium-dinucleotide interactions and a probable structural explanation for this has been provided by this study. 相似文献
19.
Hideaki Yamaguchi Yumi Kidachi Katsuyoshi Kamiie Toshiro Noshita Hironori Umetsu 《Bioinformation》2012,8(23):1147-1153
Structural analysis of the high-mobility group protein B1 (HMGB1)-DNA complex and a docking simulation between
glycyrrhetinic acid (GA) and the HMGB1-DNA complex were performed with a software package the Molecular Operating
Environment (MOE). An HMGB1-DNA (PDB code: 2GZK) was selected for the 3D structure modeling of the HMGB1-DNA
complex. The Site Finder module of the MOE identified 16 possible ligand-binding sites in the modeled HMGB1-DNA complex.
The docking simulation revealed that GA possibly inhibits functions of HMGB1 interfering with Lys90, Arg91, Ser101, Tyr149, C230 and
C231 in the HMGB1-DNA complex. To the best of our knowledge, this is the first report of an HMGB1-DNA complex with GA, and
our data verify that the GA-HMGB1-DNA model can be utilized for application to target HMGB1 for the development of antitumor
drugs.
Abbreviations
ASE-Dock - alpha sphere and excluded volume-based ligand-protein docking, CNS - central nervous system, GA - glycyrrhetinic acid, GL - glycyrrhizin, HMGB1 - high-mobility group protein B1, LBS - ligand-biding site, MOE - Molecular Operating Environment, SRY - sex-determining region on the Y chromosome. 相似文献20.
Sugimoto H Shinkyo R Hayashi K Yoneda S Yamada M Kamakura M Ikushiro S Shiro Y Sakaki T 《Biochemistry》2008,47(13):4017-4027
Vitamin D 3 (VD 3), a prohormone in mammals, plays a crucial role in the maintenance of calcium and phosphorus concentrations in serum. Activation of VD 3 requires 25-hydroxylation in the liver and 1alpha-hydroxylation in the kidney by cytochrome P450 (CYP) enzymes. Bacterial CYP105A1 converts VD 3 into 1alpha,25-dihydroxyvitamin D 3 (1alpha,25(OH) 2D 3) in two independent reactions, despite its low sequence identity with mammalian enzymes (<21% identity). The present study determined the crystal structures of a highly active mutant (R84A) of CYP105A1 from Streptomyces griseolus in complex and not in complex with 1alpha,25(OH) 2D 3. The compound 1alpha,25(OH) 2D 3 is positioned 11 A from the iron atom along the I helix within the pocket. A similar binding mode is observed in the structure of the human CYP2R1-VD 3 complex, indicating a common substrate-binding mechanism for 25-hydroxylation. A comparison with the structure of wild-type CYP105A1 suggests that the loss of two hydrogen bonds in the R84A mutant increases the adaptability of the B' and F helices, creating a transient binding site. Further mutational analysis of the active site reveals that 25- and 1alpha-hydroxylations share residues that participate in these reactions. These results provide the structural basis for understanding the mechanism of the two-step hydroxylation that activates VD 3. 相似文献