Characterization of Protein Flexibility Using Small-Angle X-Ray Scattering and Amplified Collective Motion Simulations

Large-scale flexibility within a multidomain protein often plays an important role in its biological function. Despite its inherent low resolution, small-angle x-ray scattering (SAXS) is well suited to investigate protein flexibility and determine, with the help of computational modeling, what kinds of protein conformations would coexist in solution. In this article, we develop a tool that combines SAXS data with a previously developed sampling technique called amplified collective motions (ACM) to elucidate structures of highly dynamic multidomain proteins in solution. We demonstrate the use of this tool in two proteins, bacteriophage T4 lysozyme and tandem WW domains of the formin-binding protein 21. The ACM simulations can sample the conformational space of proteins much more extensively than standard molecular dynamics (MD) simulations. Therefore, conformations generated by ACM are significantly better at reproducing the SAXS data than are those from MD simulations.     

Highly Efficient Polymer Tandem Cells and Semitransparent Cells for Solar Energy

Highly efficient tandem and semitransparent (ST) polymer solar cells utilizing the same donor polymer blended with [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) and [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM) as active layers are demonstrated. A high power conversion efficiency (PCE) of 8.5% and a record high open‐circuit voltage of 1.71 V are achieved for a tandem cell based on a medium bandgap polymer poly(indacenodithiophene‐co‐phananthrene‐quinoxaline) (PIDT‐phanQ). In addition, this approach can also be applied to a low bandgap polymer poly[2,6‐(4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b′]dithiophene)‐alt‐4,7‐(5‐fluoro‐2,1,3‐benzothia‐diazole)] (PCPDTFBT), and PCEs up to 7.9% are achieved. Due to the very thin total active layer thickness, a highly efficient ST tandem cell based on PIDT‐phanQ exhibits a high PCE of 7.4%, which is the highest value reported to date for a ST solar cell. The ST device also possesses a desirable average visible transmittance (≈40%) and an excellent color rendering index (≈100), permitting its use in power‐generating window applications.     

Validation of Catquest-9SF Questionnaire in a Chinese Cataract Population

Purpose

To develop and validate a Chinese version of the Catquest-9SF questionnaire in a cataract population.

Methods

The Catquest-9SF Questionnaire was translated and back translated into Chinese. Preoperative patients were recruited at a tertiary eye hospital and their demographic information and visual acuity were documented. Psychometric properties of the Catquest-9SF, including ordered thresholds, the ability to distinguish between different strata of person ability, absence of misfitting items, unidimentionality, differential item functioning (DIF) and construct validity were tested, using Rasch analysis.

Results

A total of 102 patients (100% response rate) were enrolled. The participants''mean age was 70.2 year (SD = 12.1) and 46.9% were female. Rasch analysis showed that this version of the questionnaire had ordered response thresholds and was free of DIF. The items fit a single overall construct and unidimensional by principal components analysis of the residuals. Patients with visual impairment had significantly poorer Rasch scores on the Catquest-9SF (mean change, -2.5, p = 0.035, compared with non-visually impaired patients).

Conclusion

The Chinese version of Catquest-9SF is a valid and reliable questionnaire for assessing the visual disability outcomes of Chinese patients with cataract, and it may be recommended for routine clinical use.     

A novel immobilization strategy using oligonucleotide as linker for small molecule microarrays construction

A novel immobilization method based on oligonucleotide as linker has been developed for small molecule microarrays (SMMs) construction. The oligonucleotide tail was employed as a linker in solid-phase synthesis. Small molecules could be easily conjugated at the 5′ end of the oligonucleotide, previously modified with a functional group. Being a reactive species, the oligonucleotide was activated by UV irradiation, for the attachment of the conjugate to the slide surface. The method was successfully applied to structurally distinct small molecules, including biotin, antibiotic and drug. This immobilization strategy showed high efficiency, 1.1 fmol of small molecules in the spotting solution per spot gave a detectable signal (mean S/N = 10.9). The results suggest that it is very promising for exploring interaction between small molecules and proteins, and high throughput detecting the chemical compounds.     

Transient Receptor Potential Vanilloid-1 (TRPV1) and Ankyrin-1 (TRPA1) Participate in Visceral Hyperalgesia in Chronic Water Avoidance Stress Rat Model

Stressfull life events have powerful influences on visceral perception of certain IBS patients. In the present study, we aimed to examine the involvement of TRPV1 and TRPA1 in the stress-induced visceral hyperalgesia. Rats were exposed to 1-h water avoidance stress (WAS) daily for 10 consecutive days. The abdominal withdrawal reflex (AWR) to colorectal distension was assessed at the end of the 10-day period. Western-blotting analysis was applied to investigate the alterations of TRPV1 and TRPA1 in the colonic afferent dorsal root ganglia (DRG). Compared with control rats, the WAS-treated rats demonstrated a significant increase in the AWR with the pressure ≥40 mm Hg (P < 0.05). Meanwhile, in the WAS-treated rats, western-blotting analysis showed significant upregulation of TRPV1 and TRPA1 in the colonic afferent DRG. The results indicate that WAS could induce the upregulation of TRPV1 and TRPA1 in the colonic afferent DRG, and both receptors may be candidate molecules involved in the stress-induced visceral hyperalgesia in rats.     

Ultrafast carotenoid-to-chlorophyll singlet energy transfer in the cytochrome b6f complex from Bryopsis corticulans

Ultrafast carotenoid-to-chlorophyll (Car-to-Chl) singlet excitation energy transfer in the cytochrome b(6)f (Cyt b(6)f) complex from Bryopsis corticulans is investigated by the use of femtosecond time-resolved absorption spectroscopy. For all-trans-alpha-carotene free in n-hexane, the lifetimes of the two low-lying singlet excited states, S(1)(2A(g)(-)) and S(2)(1B(u)(+)), are determined to be 14.3 +/- 0.4 ps and 230 +/- 10 fs, respectively. For the Cyt b(6)f complex, to which 9-cis-alpha-carotene is bound, the lifetime of the S(1)(2A(g)(-)) state remains unchanged, whereas that of the S(2)(1B(u)(+)) state is significantly reduced. In addition, a decay-to-rise correlation between the excited-state dynamics of alpha-carotene and Chl a is clearly observed. This spectroscopic evidence proves that the S(2)(1B(u)(+)) state is able to transfer electronic excitations to the Q(x) state of Chl a, whereas the S(1)(2A(g)(-)) state remains inactive. The time constant and the partial efficiency of the energy transfer are determined to be 240 +/- 40 fs and (49 +/- 4)%, respectively, which supports the overall efficiency of 24% determined with steady-state fluorescence spectroscopy. A scheme of the alpha-carotene-to-Chl a singlet energy transfer is proposed based on the excited-state dynamics of the pigments.     

Isolation of the exoelectrogenic bacterium Ochrobactrum anthropi YZ-1 by using a U-tube microbial fuel cell

Exoelectrogenic bacteria have potential for many different biotechnology applications due to their ability to transfer electrons outside the cell to insoluble electron acceptors, such as metal oxides or the anodes of microbial fuel cells (MFCs). Very few exoelectrogens have been directly isolated from MFCs, and all of these organisms have been obtained by techniques that potentially restrict the diversity of exoelectrogenic bacteria. A special U-tube-shaped MFC was therefore developed to enrich exoelectrogenic bacteria with isolation based on dilution-to-extinction methods. Using this device, we obtained a pure culture identified as Ochrobactrum anthropi YZ-1 based on 16S rRNA gene sequencing and physiological and biochemical characterization. Strain YZ-1 was unable to respire using hydrous Fe(III) oxide but produced 89 mW/m(2) using acetate as the electron donor in the U-tube MFC. Strain YZ-1 produced current using a wide range of substrates, including acetate, lactate, propionate, butyrate, glucose, sucrose, cellobiose, glycerol, and ethanol. Like another exoelectrogenic bacterium (Pseudomonas aeruginosa), O. anthropi is an opportunistic pathogen, suggesting that electrogenesis should be explored as a characteristic that confers advantages to these types of pathogenic bacteria. Further applications of this new U-tube MFC system should provide a method for obtaining additional exoelectrogenic microorganisms that do not necessarily require metal oxides for cell respiration.     

Flexible Composite Solid Electrolyte Facilitating Highly Stable “Soft Contacting” Li–Electrolyte Interface for Solid State Lithium‐Ion Batteries

A flexible composite solid electrolyte membrane consisting of inorganic solid particles (Li_1.3Al_0.3Ti_1.7(PO₄)₃), polyethylene oxide (PEO), and boronized polyethylene glycol (BPEG) is prepared and investigated. This membrane exhibits good stability against lithium dendrite, which can be attributed to its well‐designed combination components: the compact inorganic lithium ion conducting layer provides the membrane with good mechanical strength and physically barricades the free growth of lithium dendrite; while the addition of planar BPEG oligomers not only disorganizes the crystallinity of the PEO domain, leading to good ionic conductivity, but also facilitates a “soft contact” between interfaces, which not only chemically enables homogeneous lithium plating/stripping on the lithium metal anode, but also reduces the polarization effects. In addition, by employing this membrane to a LiFePO₄/Li cell and testing its galvanostatic cycling performances at 60 °C, capacities of 158.2 and 94.2 mA h g^?1 are delivered at 0.1 C and 2 C, respectively.