Inhibition of proton-transfer steps in transhydrogenase by transition metal ions

AbstractTranshydrogenase couples proton translocation across a bacterial or mitochondrial membrane to the redox reaction between NAD(H) and NADP(H). Purified intact transhydrogenase from Escherichia coli was prepared, and its His tag removed. The forward and reverse transhydrogenation reactions catalysed by the enzyme were inhibited by certain metal ions but a “cyclic reaction” was stimulated. Of metal ions tested they were effective in the order Pb2+>Cu2+>Zn2+=Cd2+>Ni2+>Co2+. The results suggest that the metal ions affect transhydrogenase by binding to a site in the proton-transfer pathway. Attenuated total-reflectance Fourier-transform infrared difference spectroscopy indicated the involvement of His and Asp/Glu residues in the Zn2+-binding site(s). A mutant in which βHis91 in the membrane-spanning domain of transhydrogenase was replaced by Lys had enzyme activities resembling those of wild-type enzyme treated with Zn2+. Effects of the metal ion on the mutant were much diminished but still evident. Signals in Zn2+-induced FTIR difference spectra of the βHis91Lys mutant were also attributable to changes in His and Asp/Glu residues but were much smaller than those in wild-type spectra. The results support the view that βHis91 and nearby Asp or Glu residues participate in the proton-transfer pathway of transhydrogenase

New q-deformed coherent states with an explicitly known resolution of unity

We construct a new family of q-deformed coherent states $|z>_q$, where $0 < q < 1$. These states are normalizable on the whole complex plane and continuous in their label $z$. They allow the resolution of unity in the form of an ordinary integral with a positive weight function obtained through the analytic solution of the associated Stieltjes power-moment problem and expressed in terms of one of the two Jacksons's $q$-exponentials. They also permit exact evaluation of matrix elements of physically-relevant operators. We use this to show that the photon number statistics for the states is sub-Poissonian and that they exhibit quadrature squeezing as well as an enhanced signal-to-quantum noise ratio over the conventional coherent state value. Finally, we establish that they are the eigenstates of some deformed boson annihilation operator and study some of their characteristics in deformed quantum optics.Comment: LaTeX, 26 pages, contains 9 eps figure

Insight into eco-friendly fabrication of silver nanoparticles by Pseudomonas aeruginosa and its potential impacts

Although green synthesis of nanoparticles (NPs) has replaced conventional physicochemical methods owing to eco-friendly and cost effective nature but molecular mechanism is not known completely. Elucidation of the mechanism is needed to enhance the production of control size synthesis and for understanding the biomineralization process. Here we report the facile, extracellular biosynthesis of silver nanoparticles (AgNPs) by Pseudomonas aeruginosa JP1 through nitrate reductase mediated mechanism. AgNO3 was reduced to AgNPs by cell filtrate exposure. UV-visible spectrum of the reaction mixture depicted reduction of ionic silver (Ag+) to atomic silver (Ag0) by a progressive upsurge in surface plasmon resonance (SPR) band range 435-450 nm. X-ray diffraction analysis showed the 2θ values at 38.08°, 44.52°, 64.42° and 77.44° confirming the crystalline nature and mean diameter [6.5-27.88nm (Ave = 13.44 nm)] of AgNPs. Transmission electron microscopy analysis demonstrated the spherical AgNPs with size range 5-45 nm. Stabilizing proteins and rhamnolipids were recognized by Fourier transform infrared spectroscopy. Nitrate reductase was purified and characterized (molecular weight 65 kDa and specific activity = 5.6 U/mg). To probe the plausible mechanism purified enzyme was retreated with AgNO3. Characteristic SPR bands range (435-450 nm) and Particle-induced x-ray emission results also confirmed the synthesis of AgNPs (59679.5 ppm) in solution. These results demonstrated that, nitrate reductase as a principal reducing agent in the mechanistic pathway of AgNPs synthesis, which leads to the understanding of metal transformation and biomineralization processes for controlling the biogeochemical cycles of silver and other heavy metals

Inappropriate stereotypical inferences? An adversarial collaboration in experimental ordinary language philosophy

This paper trials new experimental methods for the analysis of natural language reasoning and the (re)development of critical ordinary language philosophy in the wake of J.L. Austin. Philosophical arguments and thought experiments are strongly shaped by default pragmatic inferences, including stereotypical inferences. Austin suggested that contextually inappropriate stereotypical inferences are at the root of some philosophical paradoxes and problems, and that these can be resolved by exposing those verbal fallacies. This paper builds on recent efforts to empirically document inappropriate stereotypical inferences that may drive philosophical arguments. We demonstrate that previously employed questionnaire-based output measures do not suffice to exclude relevant confounds. We then report an experiment that combines reading time measurements with plausibility ratings. The study seeks to provide evidence of inappropriate stereotypical inferences from appearance verbs that have been suggested to lie at the root of the influential ‘argument from illusion’. Our findings support a diagnostic reconstruction of this argument. They provide the missing component for proof of concept for an experimental implementation of critical ordinary language philosophy that is in line with the ambitions of current ‘evidential’ experimental philosophy

Defining the industrial and engineering management professional profile: a longitudinal study based on job advertisements

The engineering professional profiles have been discussed by several branches of the engineering field. On the one hand, this discussion helps to understand the professional practice and contributes to the specification of the competences that are suitable for each function and company culture. On the other hand, it is an essential starting point for the definition of curricula in engineering schools. Thus, this study aims to characterize, in an innovative way based on job advertisements, the demand for competences and areas of practice for Industrial Engineering and Management contributing for the definition of a professional profile. This characterization is based on the analysis of 1391 job advertisements, collected during seven years from a Portuguese newspaper. The data analysis takes into account the job description in which two categories were considered: areas of professional practice (e.g. project management) and transversal competences (e.g. teamwork). Considering the total number of job advertisements, it was possible to identify 1,962 cumulative references for 11 professional practice areas and 5,261 cumulative references for transversal competences. The contribution of this study lies on the identification of the main areas of practice and the main transversal competences demanded by employers.This work was partially funded by COMPETE-POCI-01-0145-FEDER-007043 and FCT-UID-CEC-00319-2013

Quality of diabetes care and health insurance coverage: a retrospective study in an outpatient academic public hospital in Switzerland

Socioeconomic disadvantage is associated with an increased risk of adverse diabetes outcomes. In Switzerland, a country with theoretical universal healthcare coverage, people without health insurance face barriers in accessing to and in receiving standard quality care. The Geneva University Hospitals (HUG) have implemented policies aiming at reducing these gaps. We compared quality of diabetes care and ambulatory healthcare services utilization among insured and uninsured diabetic patients

Natural pH Gradients in Hydrothermal Alkali Vents Were Unlikely to Have Played a Role in the Origin of Life

The hypothesis that a natural pH gradient across inorganic membranes lying between the ocean and fluid issuing from hydrothermal alkali vents provided energy to drive chemical reactions during the origin of life has an attractive parallel with chemiosmotic ATP synthesis in present-day organisms. However, arguments raised in this review suggest that such natural pH gradients are unlikely to have played a part in life’s origin. There is as yet no evidence for thin inorganic membranes holding sharp pH gradients in modern hydrothermal alkali vents at Lost City near the Mid-Atlantic Ridge. Proposed models of non-protein forms of the H+-pyrophosphate synthase that could have functioned as a molecular machine utilizing the energy of a natural pH gradient are unsatisfactory. Some hypothetical designs of non-protein motors utilizing a natural pH gradient to drive redox reactions are plausible but complex, and such motors are deemed unlikely to have assembled by chance in prebiotic times. Small molecular motors comprising a few hundred atoms would have been unable to function in the relatively thick (&gt;1 μm) inorganic membranes that have hitherto been used as descriptive models for the natural pH gradient hypothesis. Alternative hypotheses for the evolution of chemiosmotic systems following the emergence of error-prone gene replication and translation are more likely to be correct

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified