692 research outputs found
Crystallization and Preliminary X-Ray Analysis of Human Muscle Creatine Kinase
This is the publisher's version, also available electronically from "http://scripts.iucr.org".Creatine kinase is a key enzyme in the energy homeostasis of cells and tissues with high and fluctuating energy demands. Human muscle MM creatine kinase is a dimeric protein with a molecular weight of \sim43 kDa for each subunit. It has been crystallized by the hanging-drop vapor-diffusion method using 2-methyl-2,4-pentanediol as precipitant. The crystals belong to the enantiomorphous space group P6_222 or P6_422 with cell parameters of a=b=89.11 and c=403.97 Å. The asymmetric unit of the crystal contains two subunits. A data set at 3.3 Å resolution has been collected using synchrotron radiation
Orbital density wave induced by electron-lattice coupling in orthorhombic iron pnictides
In this paper we explore the magnetic and orbital properties closely related
to a tetragonal-orthorhombic structural phase transition in iron pnictides
based on both two- and five-orbital Hubbard models. The electron-lattice
coupling, which interplays with electronic interaction, is self-consistently
treated. Our results reveal that the orbital polarization stabilizes the spin
density wave (SDW) order in both tetragonal and orthorhombic phases. However,
the ferro-orbital density wave (F-ODW) only occurs in the orthorhombic phase
rather than in the tetragonal one. Magnetic moments of Fe are small in the
intermediate Coulomb interaction region for the striped antiferromangnetic
phase in the realistic five orbital model. The anisotropic Fermi surface in the
SDW/ODW orthorhombic phase is well in agreement with the recent angle-resolved
photoemission spectroscopy experiments. These results suggest a scenario that
the magnetic phase transition is driven by the ODW order mainly arising from
the electron-lattice coupling.Comment: 21 pages, 10 figure
Study the Heavy Molecular States in Quark Model with Meson Exchange Interaction
Some charmonium-like resonances such as X(3872) can be interpreted as
possible molecular states. Within the quark model, we study
the structure of such molecular states and the similar
molecular states by taking into account of the light meson exchange (,
, , and ) between two light quarks from different
mesons
Crystal structure of human muscle creatine kinase
This is the publisher's version, also available electronically from "http://scripts.iucr.org".The crystal structure of human muscle creatine kinase has been determined by the molecular-replacement method and refined at 3.5 Å resolution. The structures of both the monomer and the dimer closely resemble those of the other known structures in the creatine kinase family. Two types of dimers, one with a non-crystallographic twofold symmetry axis and the other with a crystallographic twofold symmetry axis, were found to occur simultaneously in the crystal. These dimers form an infinite `double-helix'-like structure along an unusual long crystallographic 31 axis
Diaquabis[5-(2-pyridyl)-1H-tetrazolato-κ2 N 1,N 5]cobalt(II)
In the title compound, [Co(C6H4N5)2(H2O)2], the Co atom is bonded to two water molecules and two bidentate 5-(2-pyridyl)tetrazolate ligands resulting in a slightly distorted octahedral CoN4O2 coordination geometry. The CoII cation is situated on a crystallographic center of inversion. The asymmetric unit therefore comprises one-half of the molecule. The four N atoms belonging to two bidentate 5-(2-pyridyl)tetrazolate ligands lie in the equatorial plane and the two associated water molecules are observed in the axial coordination sites. The crystal structure exhibits a three-dimensional supramolecular network assembled by intermolecular O—H⋯N hydrogen bonds
(E)-Methyl 3-(3,4-dihydroxyphenyl)acrylate
The benzene ring in the title compound, C10H10O4, makes an angle of 4.4 (1)° with the C—C—C—O linker. The hydroxy groups are involved in both intra- and intermolecular O—H⋯O hydrogen bonds. The crystal packing is stabilized by O—H⋯O hydrogen-bonding interactions. The molecules of the caffeic acid ester form a dimeric structure in a head-to-head manner along the a axis through O—H⋯O hydrogen bonds. The dimers interact with one another through O—H⋯O hydrogen bonds, forming supermolecular chains. These chains are further extended through C—H⋯O hydrogen bonds as well as van der Waals interactions into the final three-dimensional architecture
- …