Isolation and crystal structure of the trifluoromethyl derivative C84(24)(CF3)18 of a minor C84 fullerene isomer

2020 ◽  
Vol 30 (4) ◽  
pp. 474-475
Author(s):  
Nadezhda B. Tamm ◽  
Victor A. Brotsman ◽  
Sergey I. Troyanov
Keyword(s):  
Crystal Structure ◽  
A Minor ◽  
Trifluoromethyl Derivative

scholarly journals Crystal structure of Pistol, a class of self-cleaving ribozyme

2017 ◽  
Vol 114 (5) ◽  
pp. 1021-1026 ◽  
Author(s):  
Laura A. Nguyen ◽  
Jimin Wang ◽  
Thomas A. Steitz
Keyword(s):  
Crystal Structure ◽  
Rna Structure ◽  
Tertiary Structure ◽  
Genomic Analysis ◽  
Comparative Genomic ◽  
Nonbridging Oxygen ◽  
Close Proximity ◽  
Domains Of Life ◽  
Guanine Base ◽  
A Minor

Small self-cleaving ribozymes have been discovered in all evolutionary domains of life. They can catalyze site-specific RNA cleavage, and as a result, they have relevance in gene regulation. Comparative genomic analysis has led to the discovery of a new class of small self-cleaving ribozymes named Pistol. We report the crystal structure of Pistol at 2.97-Å resolution. Our results suggest that the Pistol ribozyme self-cleavage mechanism likely uses a guanine base in the active site pocket to carry out the phosphoester transfer reaction. The guanine G40 is in close proximity to serve as the general base for activating the nucleophile by deprotonating the 2′-hydroxyl to initiate the reaction (phosphoester transfer). Furthermore, G40 can also establish hydrogen bonding interactions with the nonbridging oxygen of the scissile phosphate. The proximity of G32 to the O5′ leaving group suggests that G32 may putatively serve as the general acid. The RNA structure of Pistol also contains A-minor interactions, which seem to be important to maintain its tertiary structure and compact fold. Our findings expand the repertoire of ribozyme structures and highlight the conserved evolutionary mechanism used by ribozymes for catalysis.

scholarly journals Crystal structure and spectroscopic characterization of a cobalt(II) tetraazamacrocycle: completing a series of first-row transition-metal complexes

2017 ◽  
Vol 73 (8) ◽  
pp. 620-624 ◽  
Author(s):  
Katherine M. Van Heuvelen ◽  
Isabell Lee ◽  
Katherine Arriola ◽  
Rilke Griffin ◽  
Christopher Ye ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Spin State ◽  
Density Functional ◽  
Cobalt Complex ◽  
Chloride Ion ◽  
Spectroscopic Characterization ◽  
Spectroscopic Studies ◽  
Chloride Dihydrate ◽  
Pyramidal Geometry ◽  
A Minor

The tetraazamacrocyclic ligand 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (TMC) has been used to bind a variety of first-row transition metals but to date the crystal structure of the cobalt(II) complex has been missing from this series. The missing cobalt complex chlorido(1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane-κ4 N)cobalt(II) chloride dihydrate, [CoCl(C14H32N4)]Cl·2H2O or [CoIICl(TMC)]Cl·2H2O, crystallizes as a purple crystal. This species adopts a distorted square-pyramidal geometry in which the TMC ligand assumes the trans-I configuration and the chloride ion binds in the syn-methyl pocket of the ligand. The CoII ion adopts an S = 3 \over 2 spin state, as measured by the Evans NMR method, and UV–visible spectroscopic studies indicate that the title hydrated salt is stable in solution. Density functional theory (DFT) studies reveal that the geometric parameters of [CoIICl(TMC)]Cl·2H2O are sensitive to the cobalt spin state and correctly predict a change in spin state upon a minor perturbation to the ligand environment.

scholarly journals Crystal Structure of the N112A Mutant of the Light-Driven Sodium Pump KR2

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 496
Author(s):  
Nina Maliar ◽  
Kirill Kovalev ◽  
Christian Baeken ◽  
Taras Balandin ◽  
Roman Astashkin ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ground State ◽  
Rational Design ◽  
Sodium Pump ◽  
Ion Selectivity ◽  
Structural Data ◽  
Functional Variants ◽  
Model Protein ◽  
The Moment ◽  
A Minor

The light-driven sodium pump KR2, found in 2013 in the marine bacteria Krokinobacter eikastus, serves as a model protein for the studies of the sodium-pumping microbial rhodopsins (NaRs). KR2 possesses a unique NDQ (N112, D116, and Q123) set of the amino acid residues in the functionally relevant positions, named the NDQ motif. The N112 was shown to determine the Na+/H+ selectivity and pumping efficiency of the protein. Thus, N112A mutation converts KR2 into an outward proton pump. However, no structural data on the functional conversions of the light-driven sodium pumps are available at the moment. Here we present the crystal structure of the N112A mutant of KR2 in the ground state at the resolution of 2.4 Å. The structure revealed a minor deflection in the central part of the helix C and a double conformation of the L74 residue in the mutant. The organization of the retinal Schiff base and neighboring water molecules is preserved in the ground state of KR2-N112A. The presented data provide structural insights into the effects of the alterations of the characteristic NDQ motif of NaRs. Our findings also demonstrate that for the rational design of the KR2 variants with modified ion selectivity for optogenetic applications, the structures of the intermediate states of both the protein and its functional variants are required.

scholarly journals Crystal structure ofN-(quinolin-6-yl)hydroxylamine

2014 ◽  
Vol 70 (11) ◽  
pp. 322-324 ◽  
Author(s):  
Anuruddha Rajapakse ◽  
Roman Hillebrand ◽  
Sarah M. Lewis ◽  
Zachary D. Parsons ◽  
Charles L. Barnes ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Asymmetric Unit ◽  
Π Interactions ◽  
Compound C ◽  
Independent Molecules ◽  
A Minor

The title compound, C9H8N2O, crystallized with four independent molecules in the asymmetric unit. The four molecules are linkedviaone O—H...N and two N—H...N hydrogen bonds, forming a tetramer-like unit. In the crystal, molecules are further linked by O—H...N and N—H...O hydrogen bonds forming layers parallel to (001). These layers are linkedviaC—H...O hydrogen bonds and a number of weak C—H...π interactions, forming a three-dimensional structure. The crystal was refined as a non-merohedral twin with a minor twin component of 0.319.

Crystal Structure Determination of N-(para-Chlorophenyl) Phthalimide and Analysis of its Formation from N-(para-Chlorophenyl) Phthalanilic Acid

1974 ◽  
Vol 29 (11-12) ◽  
pp. 769-779 ◽  
Author(s):  
B. L. Farmer ◽  
J. B. Lando
Keyword(s):  
Crystal Structure ◽  
Molecular Mechanism ◽  
Structure Determination ◽  
Crystalline Phase ◽  
Molecular Motion ◽  
High Energy ◽  
Cyclization Reaction ◽  
Bond Rotation ◽  
A Minor

Crystalline N-(para-chlorophenyl) phthalanilic acid undergoes a topochemical cyclization reaction with the elimination of water yielding crystalline N-(para-chlorophenyl) phthalimide. The crystal structure of the imide product has been determined and compared to the previously determined structure of the reactant. The reaction from this particular crystalline phase of N-(para-chlorophenyl) phthalanilic acid is enhanced by the presence of a high energy molecular conformer of the acid, little molecular motion necessary for reaction, and only a minor rearrangement required to pack into the imide structure after the reaction. A detailed molecular mechanism for this reaction is proposed involving some bond rotation, but little movement of the molecule as a whole.

Structural characterization of anhydrous and bishydrated calcium hexafluorosilicate by powder diffraction methods

2011 ◽  
Vol 26 (4) ◽  
pp. 308-312 ◽  
Author(s):  
Simone Frisoni ◽  
Stefano Brenna ◽  
Norberto Masciocchi
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Space Group ◽  
Cell Parameters ◽  
Thermal Expansion Coefficients ◽  
Full Profile ◽  
A Minor

The synthesis and X-ray powder diffraction data for the long-known CaSiF6 and CaSiF6·2H2O species are reported. Their crystal structures have been determined from laboratory powder diffraction data by simulated annealing and full-profile Rietveld refinement methods. CaSiF6·2H2O was found to crystallize in the monoclinic P21/n space group with unit-cell parameters: a = 10.48107(9), b = 9.18272(7), c = 5.72973(5) Å, β = 98.9560(6)°, V = 544.733(8) Å3, and Z = 4. The crystal structure of CaSiF6·2H2O, eventually found to be isomorphous with SrSiF6·2H2O (but not with the Mg analogue—a hexahydrate phase), contains centrosymmetric [Ca(μ-H2O)2Ca]4+ dimers, interconnected by hexafluorosilicate anions, in a dense 3D framework. The crystal structure is completed by a further water molecule, terminally bound to the Ca2+ ion, which, consequently, attains a F5O3 octacoordination. Thermodiffractometric measurements allowed the determination of the linear and volumetric thermal expansion coefficients of CaSiF6·2H2O, which showed a minor contraction, along a, on heating. CaSiF6 is trigonal, space group R-3, a = 5.3497(3), c = 13.5831(11) Å, V = 336.66(5) Å3, and Z = 3, and isomorphous with several other species of MIIAIVF6 or MIAVF6 formulation, among which several silicates, germanates, and stannates.

scholarly journals Crystal structure of timothy grass allergen Phl p 12.0101 reveals an unusual profilin dimer

2021 ◽  
Author(s):  
Andrea O’Malley ◽  
A. Brenda Kapingidza ◽  
Noah Hyduke ◽  
Coleman Dolamore ◽  
Krzysztof Kowal ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Grass Pollen ◽  
Cross Reactivity ◽  
Timothy Grass ◽  
Phl P 5 ◽  
Allergy Diagnostics ◽  
Structure Similarity ◽  
Minor Allergens ◽  
A Minor ◽  
Minor Allergen

Timothy grass pollen is a source of potent allergens. Among them, Phl p 1 and Phl p 5 are thought to be the most important, as a majority of timothy grass-allergic individuals have IgE antibodies directed against these two allergens. The profilin from timothy grass (Phl p 12) has been registered as a minor allergen, with up to 35% of individuals in populations of grass pollen allergic patients showing IgE binding to Phl p 12. Profilins are primarily minor allergens and are known for a high likelihood of co-sensitization as well as cross-reactivity situations caused by their sequence and structure similarity. The crystal structure of Phl p 12.0101 was determined and it revealed that this allergen may form an unusual dimer not previously observed among any profilins. For example, the Phl p 12 dimer has a completely different geometry and interface when compared with the latex profilin (Hev b 8) dimer that has its crystal structure determined. The structure of Phl p 12.0101 is described in the context of allergenic sensitization and allergy diagnostics. Moreover, the structure of the Phl p 12.0101 dimer is discussed, taking into account the production of recombinant allergens and their storage.

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