Ribonucleotide reductases (RNRs) are a diverse family of enzymes that are alone capable of generating 2'-deoxynucleotides de novo and are thus critical in DNA biosynthesis and repair. The nucleotide ...reduction reaction in all RNRs requires the generation of a transient active site thiyl radical, and in class I RNRs, this process involves a long-range radical transfer between two subunits, α and β. Because of the transient subunit association, an atomic resolution structure of an active α2β2 RNR complex has been elusive. We used a doubly substituted β2, E52Q/(2,3,5)-trifluorotyrosine122-β2, to trap wild-type α2 in a long-lived α2β2 complex. We report the structure of this complex by means of cryo-electron microscopy to 3.6-angstrom resolution, allowing for structural visualization of a 32-angstrom-long radical transfer pathway that affords RNR activity.
Background
This study marks the first epidemiological evaluation of the prevalence and burden of chronic neuropathic pain (NeP) in an Asian population. The objective of this nationwide ...cross‐sectional study was to identify the characteristics of individuals with NeP, detect the NeP features that affect their quality of life (QOL), and demonstrate the negative effects of NeP on social and daily living as well as comorbidities including depression, anxiety and sleep disorders.
Methods
We mailed a cross‐sectional, population‐based epidemiological survey to a random nationwide sample of 10,000 Japanese adults over 20 years old.
Results
The response rate was 54.4% (2445 men, 2992 women; mean age, 53.4 years). Prevalence of chronic pain was 16.6%, and prevalence of NeP was 3.2% as detected by the PainDETECT. Participants with NeP showed significantly lower quality of life according to scores on the EuroQol‐5 Dimensions scale (p < 0.001), higher levels of psychological distress on the Kessler 6‐item psychological distress scale (p < 0.001), poorer sleep quality (p < 0.001), and more workdays lost (p < 0.001) than did participants without NeP. Linear regression modelling showed that widespread pain, thermal hyperalgesia and pressure‐induced pain had strong associations with lower QOL, with regression coefficients of −0.046 (p < 0.001), −0.038 (p < 0.001), and −0.040 (p < 0.001), respectively.
Conclusions
This study is the first to report the prevalence of NeP in an Asian population using a validated questionnaire. This study provides compelling evidence that chronic NeP is more strongly associated with poorer QOL, mental health and social well‐being than CP without a neuropathic component.
Significance
This population‐based nationwide epidemiological study revealed the prevalence, characteristics, and negative effects of chronic pain with neuropathic components in Asian society. The prevalence of neuropathic pain was 3.2% with PainDETECT.
A set of C43(DE3) and BL21(DE3) Escherichia coli host strains that are auxotrophic for various amino acids is briefly reviewed. These strains require the addition of a defined set of one or more ...amino acids in the growth medium, and have been specifically designed for overproduction of membrane or water-soluble proteins selectively labelled with stable isotopes, such as 2H, 13C and 15N. The strains described here are available for use and have been deposited into public strain banks. Although they cannot fully eliminate the possibility of isotope dilution and mixing, metabolic scrambling of the different amino acid types can be minimized through a careful consideration of the bacterial metabolic pathways. The use of a suitable auxotrophic expression host strain with an appropriately isotopically labelled growth medium ensures high levels of isotope labelling efficiency as well as selectivity for providing deeper insight into protein structure-function relationships.
The local atomic structure in two types of Tsai-type 1/1 quasicrystal approximants in the Au-Ge-Yb system were observed using scanning transmission electron microscopy (STEM). The high-angle annular ...dark-field (HAADF) imaging method in STEM was employed to detect the difference in local atomic structure at the cluster centers for both compounds. Two types of cluster centers were observed in the different compounds: a tetrahedron with various orientations and a single Yb atom. Furthermore, atomic-resolution energy-dispersive X-ray spectroscopy showed direct evidence for the presence of a single Yb atom at the cluster center for the later compound.
Ribonucleotide reductases (RNR) catalyze the reduction of nucleotides to deoxynucleotides through a mechanism involving an essential cysteine based thiyl radical. In the E. coli class 1a RNR the ...thiyl radical (C439 •) is a transient species generated by radical transfer (RT) from a stable diferric-tyrosyl radical cofactor located >35 Å away across the α2:β2 subunit interface. RT is facilitated by sequential proton-coupled electron transfer (PCET) steps along a pathway of redox active amino acids (Y122β ↔ W48β? ↔ Y356β ↔ Y731α ↔ Y730α ↔ C439α). The mutant R411A(α) disrupts the H-bonding environment and conformation of Y731, ostensibly breaking the RT pathway in α2. However, the R411A protein retains significant enzymatic activity, suggesting Y731 is conformationally dynamic on the time scale of turnover. Installation of the radical trap 3-amino tyrosine (NH2Y) by amber codon suppression at positions Y731 or Y730 and investigation of the NH2Y• trapped state in the active α2:β2 complex by HYSCORE spectroscopy validate that the perturbed conformation of Y731 in R411A-α2 is dynamic, reforming the H-bond between Y731 and Y730 to allow RT to propagate to Y730. Kinetic studies facilitated by photochemical radical generation reveal that Y731 changes conformation on the ns−μs time scale, significantly faster than the enzymatic k cat. Furthermore, the kinetics of RT across the subunit interface were directly assessed for the first time, demonstrating conformationally dependent RT rates that increase from 0.6 to 1.6 × 104 s–1 when comparing wild type to R411A-α2, respectively. These results illustrate the role of conformational flexibility in modulating RT kinetics by targeting the PCET pathway of radical transport.
The aim of this study was the development of an innovative biocompatible sealant composed of Alaska pollock-derived gelatin partially modified with a dodecyl group (C12-ApGltn) and a poly(ethylene ...glycol)-based crosslinker, pentaerythritol poly(ethylene glycol) ether tetrasuccinimidyl glutarate. The burst strength of the developed sealants was measured using porcine aorta and rat lungs. The maximum burst strength of a C12-ApGltn-based sealant against the porcine aorta was 4-fold higher than that of an original ApGltn (Org-ApGltn)-based sealant. No significant increase in the burst strength was observed between C12-ApGltn-based sealants with 4.2 and 8.9 mol% modification ratios. From histological observation after burst strength measurement, tissue tearing was observed when a C12-ApGltn-based sealant was applied. In contrast, the Org-ApGltn-based sealant was peeled away from the aorta surface due to cohesion failure. Similar to the porcine aorta, the burst strength of C12-ApGltn-based sealants applied on a rat lung defect was 3-fold higher than that of an Org-ApGltn-based sealant. The curing time of the C12-ApGltn-based sealant measured by a simple mixing method was shorter (2.6 ± 0.1 s) than that of the Org-ApGltn-based sealant (4.1 ± 0.3 s). The swelling ratio of the C12-ApGltn-based sealant (23.7 ± 3.1) was significantly lower than that of the Org-ApGltn-based sealant (32.3 ± 1.1). The C12-ApGltn-based sealant was completely degraded within 28 days after implantation in the backs of rats without a severe inflammation reaction. However, the Org-ApGltn-based sealant disappeared within 14 days. These results indicated that hydrophobically-modified ApGltn has an effective sealing effect on moist tissues and biocompatibility in vivo.
Past studies have shown that incubation of human serum samples on high density peptide arrays followed by measurement of total antibody bound to each peptide sequence allows detection and ...discrimination of humoral immune responses to a variety of infectious diseases. This is true even though these arrays consist of peptides with near-random amino acid sequences that were not designed to mimic biological antigens. This "immunosignature" approach, is based on a statistical evaluation of the binding pattern for each sample but it ignores the information contained in the amino acid sequences that the antibodies are binding to. Here, similar array-based antibody profiles are instead used to train a neural network to model the sequence dependence of molecular recognition involved in the immune response of each sample. The binding profiles used resulted from incubating serum from 5 infectious disease cohorts (Hepatitis B and C, Dengue Fever, West Nile Virus and Chagas disease) and an uninfected cohort with 122,926 peptide sequences on an array. These sequences were selected quasi-randomly to represent an even but sparse sample of the entire possible combinatorial sequence space (~1012). This very sparse sampling of combinatorial sequence space was sufficient to capture a statistically accurate representation of the humoral immune response across the entire space. Processing array data using the neural network not only captures the disease-specific sequence-binding information but aggregates binding information with respect to sequence, removing sequence-independent noise and improving the accuracy of array-based classification of disease compared with the raw binding data. Because the neural network model is trained on all samples simultaneously, a highly condensed representation of the differential information between samples resides in the output layer of the model, and the column vectors from this layer can be used to represent each sample for classification or unsupervised clustering applications.
In the accelerator driven system, oxygen sensors, on which yttria-stabilized-zirconia (YSZ) is used for the electrolyte, will be irradiated by gamma-ray in activated lead bismuth eutectic (LBE) ...adopted as a both coolant and spallation target. Partially stabilized zirconia, like a 3Y-YSZ, has high strength due to the stress induced phase transformation from tetragonal (T) to monoclinic (M) phase. The mechanical properties of YSZ specimens after gamma-ray irradiation, thermal aging and immersion in LBE have been investigated in terms of the fracture surface structure. In the case of 6Y and 8Y-YSZ, the 4-point bend strength did not change even after gamma-ray irradiation and thermal aging. The 3Y-YSZ, however, showed that the strength was decreased a little by the gamma-ray irradiation, thermal aging and also immersion in LBE. The XRD results indicate that in the case of 3Y-YSZ after the annealing and soaking in LBE, the pristine surface, which is not fractured and strained by bending test, shows M phase much more than the surface of as-received one. After surface polishing of 3Y-YSZ the XRD intensity of M phase increased with increasing gamma-ray dose for the pristine surface. The bend strength of irradiated 3Y-YSZ after polishing, however, did not change in this study. These results suggest that the process of gamma-ray irradiation and thermal process around 450 °C cause pre-phase transformation from T to M, which prevents the stress induced phase transformation previously.
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