Abstract
In addition to the serotonin 5-HT
2A
receptor (5-HT
2A
R), the dopamine D
2
receptor (D
2
R) is a key therapeutic target of antipsychotics for the treatment of schizophrenia. The inactive ...state structures of D
2
R have been described in complex with the inverse agonists risperidone (D
2
R
ris
) and haloperidol (D
2
R
hal
). Here we describe the structure of human D
2
R in complex with spiperone (D
2
R
spi
). In D
2
R
spi
, the conformation of the extracellular loop (ECL) 2, which composes the ligand-binding pocket, was substantially different from those in D
2
R
ris
and D
2
R
hal
, demonstrating that ECL2 in D
2
R is highly dynamic. Moreover, D
2
R
spi
exhibited an extended binding pocket to accommodate spiperone’s phenyl ring, which probably contributes to the selectivity of spiperone to D
2
R and 5-HT
2A
R. Together with D
2
R
ris
and D
2
R
hal
, the structural information of D
2
R
spi
should be of value for designing novel antipsychotics with improved safety and efficacy.
Sediment, soil and drainage water were collected at an abandoned copper mine, and the leachate copper prepared with 1M HCl were qualitatively analyzed by a handy elemental analyzer based on liquid ...electrode plasma atomic emission spectrometry (LEP-AES). Quantitative values obtained by the handy analyzer with standard addition or conventional calibration method combining with self-internal standard method, and ones by flame atomic absorption spectrometer were compared. The analytical condition for LEP-AES, the accuracy and the precision were discussed. The elongation of interval of pulsed applied voltage enhanced intensities of emission line, but background rising for copper emission line overlapping tail of broad OH band prevent expected improvement of the limit of detection. Copper species in sediment exist as divalent basic copper sulfate confirmed by XANES/EXAFS spectra recorded by a laboratory type spectrometer.
Time-resolved serial femtosecond crystallography using an X-ray free electron laser (XFEL) in conjunction with a photosensitive caged-compound offers a crystallographic method to track enzymatic ...reactions. Here we demonstrate the application of this method using fungal NO reductase, a heme-containing enzyme, at room temperature. Twenty milliseconds after caged-NO photolysis, we identify a NO-bound form of the enzyme, which is an initial intermediate with a slightly bent Fe-N-O coordination geometry at a resolution of 2.1 Å. The NO geometry is compatible with those analyzed by XFEL-based cryo-crystallography and QM/MM calculations, indicating that we obtain an intact Fe
-NO coordination structure that is free of X-ray radiation damage. The slightly bent NO geometry is appropriate to prevent immediate NO dissociation and thus accept H
from NADH. The combination of using XFEL and a caged-compound is a powerful tool for determining functional enzyme structures during catalytic reactions at the atomic level.
Cross‐brace structural motifs are required as a scaffold to design artificial RING fingers (ARFs) that function as ubiquitin ligase (E3) in ubiquitination and have specific ubiquitin‐conjugating ...enzyme (E2)‐binding capabilities. The Simple Modular Architecture Research Tool database predicted the amino acid sequence 131–190 (KIAA1045ZF) of the human KIAA1045 protein as an unidentified structural region. Herein, the stoichiometry of zinc ions estimated spectrophotometrically by the metallochromic indicator revealed that the KIAA1045ZF motif binds to two zinc atoms. The structure of the KIAA1045ZF motif bound to the zinc atoms was elucidated at the atomic level by nuclear magnetic resonance. The actual structure of the KIAA1045ZF motif adopts a C4HC3‐type PHD fold belonging to the cross‐brace structural family. Therefore, the utilization of the KIAA1045ZF motif as a scaffold may lead to the creation of a novel ARF.
PDB Code(s): 5XHT
Since conducted and radiated noise from motor systems such as HEVs affects AM radio and other in-vehicle electronic devices, the level of that noise is specified in CISPR25. The radiated noise ...prediction method of the motor system bench was constructed based on combination of measurement data and electromagnetic field analysis. The key point of this method is to model the return path of the common mode current including the environment around the bench.
Cytochrome c oxidase catalyses the reduction of molecular oxygen to water while the energy released in this process is used to pump protons across a biological membrane. Although an extremely ...well-studied biological system, the molecular mechanism of proton pumping by cytochrome c oxidase is still not understood. Here we report a method to produce large quantities of highly diffracting microcrystals of ba
-type cytochrome c oxidase from Thermus thermophilus suitable for serial femtosecond crystallography. The room-temperature structure of cytochrome c oxidase is solved to 2.3 Å resolution from data collected at an X-ray Free Electron Laser. We find overall agreement with earlier X-ray structures solved from diffraction data collected at cryogenic temperature. Previous structures solved from synchrotron radiation data, however, have shown conflicting results regarding the identity of the active-site ligand. Our room-temperature structure, which is free from the effects of radiation damage, reveals that a single-oxygen species in the form of a water molecule or hydroxide ion is bound in the active site. Structural differences between the ba
-type and aa
-type cytochrome c oxidases around the proton-loading site are also described.
Photo-cross-linkable liquid crystalline polymers (PLCPs) comprised of a 4-methoxycinnamoyloxy group connected with a tolane moiety possessing methyl substituents were synthesized in order to ...investigate the influence of methyl substituents on the thermally enhanced in-plane molecular reorientation of thin films. Different wavelengths from a UV light source were used to evaluate the effect of the photoreaction of the cinnamate and tolane moieties. For all PLCP films, thermally enhanced photoinduced molecular reorientation was observed, but the reorientation order and its direction greatly depended on the position and the number of the methyl substituents as well as the wavelength of light. A smaller degree of photoreaction was sufficient for effective molecular reorientation when the photoreaction of the tolane moiety was restricted.
Photosystem II (PSII) is a huge membrane-protein complex consisting of 20 different subunits with a total molecular mass of 350 kDa for a monomer. It catalyses light-driven water oxidation at its ...catalytic centre, the oxygen-evolving complex (OEC). The structure of PSII has been analysed at 1.9 Å resolution by synchrotron radiation X-rays, which revealed that the OEC is a Mn
CaO
cluster organized in an asymmetric, 'distorted-chair' form. This structure was further analysed with femtosecond X-ray free electron lasers (XFEL), providing the 'radiation damage-free' structure. The mechanism of O=O bond formation, however, remains obscure owing to the lack of intermediate-state structures. Here we describe the structural changes in PSII induced by two-flash illumination at room temperature at a resolution of 2.35 Å using time-resolved serial femtosecond crystallography with an XFEL provided by the SPring-8 ångström compact free-electron laser. An isomorphous difference Fourier map between the two-flash and dark-adapted states revealed two areas of apparent changes: around the Q
/non-haem iron and the Mn
CaO
cluster. The changes around the Q
/non-haem iron region reflected the electron and proton transfers induced by the two-flash illumination. In the region around the OEC, a water molecule located 3.5 Å from the Mn
CaO
cluster disappeared from the map upon two-flash illumination. This reduced the distance between another water molecule and the oxygen atom O4, suggesting that proton transfer also occurred. Importantly, the two-flash-minus-dark isomorphous difference Fourier map showed an apparent positive peak around O5, a unique μ
-oxo-bridge located in the quasi-centre of Mn1 and Mn4 (refs 4,5). This suggests the insertion of a new oxygen atom (O6) close to O5, providing an O=O distance of 1.5 Å between these two oxygen atoms. This provides a mechanism for the O=O bond formation consistent with that proposed previously.
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