Labeling strategy and signal broadening mechanism of Protein NMR spectroscopy in Xenopus laevis oocytes.

We used Xenopus laevis oocytes, a paradigm for a variety of biological studies, as a eukaryotic model system for in-cell protein NMR spectroscopy. The small globular protein GB1 was one of the first studied in Xenopus oocytes, but there have been few reports since then of high-resolution spectra in oocytes. The scarcity of data is at least partly due to the lack of good labeling strategies and the paucity of information on resonance broadening mechanisms.

Size-dependent sorption of myo-inositol hexakisphosphate and orthophosphate on nano-γ-Al2O3.

The effects of particle size (5, 35 and 70nm) on the sorption of myo-inositol hexakisphosphate (IHP) and inorganic phosphate (KH2PO4, Pi) on γ-Al2O3 nanoparticles were investigated using batch sorption experiments, zeta potential measurements and solid-state nuclear magnetic resonance spectroscopy (NMR). The results show that the maximum sorption densities (μmolm(-2)) for IHP and Pi increase with decreasing γ-Al2O3 particle size. The sorption affinity of γ-Al2O3 for IHP and Pi generally increases with decreasing particle size, and the sorption affinity for IHP is approximately one order of magnitude greater than that for Pi.

Altered spontaneous brain activity in patients with acute spinal cord injury revealed by resting-state functional MRI.

Background: Previous neuroimaging studies have provided evidence of structural and functional reorganization of brain in patients with chronic spinal cord injury (SCI). However, it remains unknown whether the spontaneous brain activity changes in acute SCI. In this study, we investigated intrinsic brain activity in acute SCI patients using a regional homogeneity (ReHo) analysis based on resting-state functional magnetic resonance imaging.

Bilateral common carotid artery occlusion induced brain lesions in rats: A longitudinal diffusion tensor imaging study.

Bilateral common carotid artery occlusion (BCCAO) has been widely used to reproduce the white matter (WM) and gray matter (GM) damage associated with chronic cerebral hypoperfusion (CCH). This study investigated whether diffusion tensor imaging (DTI) could be used at the early stages of disease to assess brain damage induced by BCCAO. To this end, DTI, together with histological methods, was used to evaluate the progression of WM lesions and GM neurodegeneration following BCCAO.

Exploring the ring current of carbon nanotubes by first-principles calculations.

Ring current is a fundamental concept to understand the nuclear magnetic resonance (NMR) properties and aromaticity for conjugated systems, such as carbon nanotubes (CNTs). Employing the recently developed gauge including projector augmented wave (GIPAW) method, we studied the ring currents of CNTs systematically and visualized their distribution. The ring current patterns are determined by the semiconducting or metallic properties of CNTs.

Dual emission behavior of phenyleneethynylene gold(I) complexes dictated by intersystem crossing: a theoretical perspective.

In commonly studied gold(I) complexes with oligo (o-, p-, or m-phenyleneethynylene) (PE) ligands, an intriguing photophysical behavior is dual emission composed of fluorescence from S1 and phosphorescence from T1 which is dictated by effective intersystem crossing (ISC) process. In order to explore the salient photodynamics of such oligo-PE gold(I) complexes effectively, we have deliberately chosen three model complexes, namely, Ph-C≡C-Au(PMe3) (1a') and Ph-C≡C-(1,m)C6H4-C≡C-Au(PMe3) (m=4, 2a'; m=3, 3a') in place of the real system. Firstly, electronic structure methods based on DFT and TD-DFT are utilized to perform optimization calculations for the ground- and lowest-lying excited states, respectively.

A critical role for interferon regulatory factor 9 in cerebral ischemic stroke.

The failure of past efforts to develop effective stroke treatments is at least partially because these treatments often interfered with essential physiological functions, even though they are targeted toward pathophysiological events, such as inflammation, excitotoxicity, and oxidative stress. Thus, the direct targeting of endogenous neuroprotective or destructive elements holds promise as a potential new approach to treating this devastating condition. Interferon regulatory factor 9 (IRF9), a transcription factor that regulates innate immune responses, has been implicated in neurological pathology.

New insight into the hydrocarbon-pool chemistry of the methanol-to-olefins conversion over zeolite H-ZSM-5 from GC-MS, solid-state NMR spectroscopy, and DFT calculations.

Over zeolite H-ZSM-5, the aromatics-based hydrocarbon-pool mechanism of methanol-to-olefins (MTO) reaction was studied by GC-MS, solid-state NMR spectroscopy, and theoretical calculations. Isotopic-labeling experimental results demonstrated that polymethylbenzenes (MBs) are intimately correlated with the formation of olefin products in the initial stage. More importantly, three types of cyclopentenyl cations (1,3-dimethylcyclopentenyl, 1,2,3-trimethylcyclopentenyl, and 1,3,4-trimethylcyclopentenyl cations) and a pentamethylbenzenium ion were for the first time identified by solid-state NMR spectroscopy and DFT calculations under both co-feeding ([(13) C6 ]benzene and methanol) conditions and typical MTO working (feeding [(13) C]methanol alone) conditions.

Rotational mode specificity in the Cl + CHD3 → HCl + CD3 reaction.

By exciting the rotational modes of vibrationally excited CHD3(v1 = 1, JK), the reactivity for the Cl + CHD3 → HCl + CD3 reaction is observed enhanced by as much as a factor of two relative to the rotationless reactant. To understand the mode specificity, the reaction dynamics was studied using both a reduced-dimensional quantum dynamical model and the conventional quasi-classical trajectory method, both of which reproduced qualitatively the measured enhancements. The mechanism of enhancement was analyzed using a Franck-Condon model and by inspecting trajectories.

Visualizing an ultra-weak protein-protein interaction in phosphorylation signaling.

Proteins interact with each other to fulfill their functions. The importance of weak protein-protein interactions has been increasingly recognized. However, owing to technical difficulties, ultra-weak interactions remain to be characterized.

Alkylation of benzene with carbon monoxide over Zn/H-ZSM-5 zeolite studied using in situ solid-state NMR spectroscopy.

Using in situ solid-state NMR spectroscopy we show that CO can act as an alkylating reagent and react with benzene to produce toluene over a Zn/H-ZSM-5 zeolite. In the alkylation reaction, CO provides the methyl group of toluene via a methoxy intermediate.

Control for a synchronization-desynchronization switch.

How to freely enhance or suppress synchronization of networked dynamical systems is of great importance in many disciplines. A unified precise control method for a synchronization-desynchronization switch, called the pull-push control method, is suggested. Namely, synchronization can be achieved when the original systems are desynchronous by pulling (or protecting) one node or a certain subset of nodes, whereas desynchronization can be accomplished when the systems are already synchronous by pushing (or kicking) one node or a certain subset of nodes.

Solid-state NMR shows that dynamically different domains of membrane proteins have different hydration dependence.

Hydration has a profound influence on the structure, dynamics, and functions of membrane and membrane-embedded proteins. So far the hydration response of molecular dynamics of membrane proteins in lipid bilayers is poorly understood. Here, we reveal different hydration dependence of the dynamics in dynamically different domains of membrane proteins by multidimensional magic angle spinning (MAS) solid-state NMR (ssNMR) spectroscopy using 121-residue integral diacylglycerol kinase (DAGK) in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DMPG) lipid bilayers as a model system.

Altered brain functional networks in heavy smokers.

Recent neuroimaging studies have demonstrated that cigarette smoking is associated with changed brain structure and function. However, little is known about alterations of the topological organization of brain functional networks in heavy smokers. Thirty-one heavy smokers and 33 non-smokers underwent a resting-state functional magnetic resonance imaging scan.

The molecular structure of Alzheimer β-amyloid fibrils formed in the presence of phospholipid vesicles.

β-amyloid (Aβ) fibrils are the major species involved in Alzheimer's disease (AD). An atomic-resolution molecular structure of Aβ40 fibrils formed in the presence of lipid vesicles was obtained by using magic angle spinning (MAS) solid-state NMR spectroscopy. The fibril structures formed in the presence of the lipid vesicles are remarkably different from those formed in solution.

Conformation and topology of diacylglycerol kinase in E.coli membranes revealed by solid-state NMR spectroscopy.

Solid-state NMR is a powerful tool for studying membrane proteins in a native-like lipid environment. 3D magic angle spinning (MAS) NMR was employed to characterize the structure of E.coli diacylglycerol kinase (DAGK) reconstituted into its native E.

Clustering versus non-clustering phase synchronizations.

Clustering phase synchronization (CPS) is a common scenario to the global phase synchronization of coupled dynamical systems. In this work, a novel scenario, the non-clustering phase synchronization (NPS), is reported. It is found that coupled systems do not transit to the global synchronization until a certain sufficiently large coupling is attained, and there is no clustering prior to the global synchronization.

Asymmetric simultaneous phase-inversion cross-polarization in solid-state MAS NMR: relaxing selective polarization transfer condition between two dilute spins.

Double cross polarization (DCP) has been widely used for heteronuclear polarization transfer between (13)C and (15)N in solid-state magic-angle spinning (MAS) NMR. However, DCP is such sensitive to experimental settings that small variations or deviations in RF fields would deteriorate its efficiency. Here, we report on asymmetric simultaneous phase-inversion cross polarization (referred as aSPICP) for selective polarization transfer between low-γ (13)C and (15)N spins.

Altered spontaneous brain activity in primary open angle glaucoma: a resting-state functional magnetic resonance imaging study.

Background: Previous studies demonstrated that primary open angle glaucoma (POAG) is associated with abnormal brain structure; however, little is known about the changes in the local synchronization of spontaneous activity. The main objective of this study was to investigate spontaneous brain activity in patients with POAG using regional homogeneity (ReHo) analysis based on resting state functional magnetic resonance imaging (rs-fMRI).

Methodology/principal Findings: Thirty-nine POAG patients and forty-one age- and gender- matched healthy controls were finally included in the study.

Highly mobile segments in crystalline poly(ethylene oxide)8:NaPF6 electrolytes studied by solid-state NMR spectroscopy.

Two types of high-crystallinity poly(ethylene oxide)/NaPF6 electrolytes with ethylene oxide (EO)/Na molar ratios of 8:1 and 6:1, termed as PEO8:NaPF6 and PEO6:NaPF6 with Mw = 6000 g mol(-1) were prepared, and their ionic conductivity, structure, and segmental motions were investigated and compared. PEO8:NaPF6 polymer electrolyte exhibits the room-temperature ionic conductivity 7.7 × 10(-7) S cm(-1) which is about five times higher than the PEO6:NaPF6.

Subtle dynamics of holo glutamine binding protein revealed with a rigid paramagnetic probe.

Bacterial periplasmic binding proteins (PBPs) are involved in the translocation of small molecules in the periplasm. To unload, the two domains of a PBP open up, allowing the ligand to exit. However, it is not clear whether there are dynamics near the binding site which can facilitate the rapid dissociation of a ligand.

IRF4 is a novel mediator for neuronal survival in ischaemic stroke.

Neuroprotection following ischaemic stroke is driven by the interplay between regulatory transcription factors and endogenous protective factors. IRF4, a member of the interferon regulatory factor (IRF) family, is implicated in the survival of tumour cells. However, its role in the survival of normal cells including neurons remains elusive.

Intermittent and sustained periodic windows in networked chaotic Rössler oscillators.

Route to chaos (or periodicity) in dynamical systems is one of fundamental problems. Here, dynamical behaviors of coupled chaotic Rössler oscillators on complex networks are investigated and two different types of periodic windows with the variation of coupling strength are found. Under a moderate coupling, the periodic window is intermittent, and the attractors within the window extremely sensitively depend on the initial conditions, coupling parameter, and topology of the network.

Matching rules for collective behaviors on complex networks: optimal configurations for vibration frequencies of networked harmonic oscillators.

The structure-dynamics-function has become one of central problems in modern sciences, and it is a great challenge to unveil the organization rules for different dynamical processes on networks. In this work, we study the vibration spectra of the classical mass spring model with different masses on complex networks, and pay our attention to how the mass spatial configuration influences the second-smallest vibrational frequency (ω2) and the largest one (ωN). For random networks, we find that ω2 becomes maximal and ωN becomes minimal if the node degrees are point-to-point-positively correlated with the masses.

Membrane attachment and structure models of lipid storage droplet protein 1.

Neutral lipid triglycerides, a main reserve for fat and energy, are stored in organelles called lipid droplets. The storage and release of triglycerides are actively regulated by several proteins specific to the droplet surface, one of which in insects is PLIN1. PLIN1 plays a key role in the activation of triglyceride hydrolysis upon phosphorylation.