Search results for " DEGRADATION"

Structure of Rhodococcus erythropolis limonene-1,2-epoxide hydrolase reveals a novel active site

2003

Epoxide hydrolases are essential for the processing of epoxide-containing compounds in detoxification or metabolism. The classic epoxide hydrolases have an alpha/beta hydrolase fold and act via a two-step reaction mechanism including an enzyme-substrate intermediate. We report here the structure of the limonene-1,2-epoxide hydrolase from Rhodococcus erythropolis, solved using single-wavelength anomalous dispersion from a selenomethionine-substituted protein and refined at 1.2 A resolution. This enzyme represents a completely different structure and a novel one-step mechanism. The fold features a highly curved six-stranded mixed beta-sheet, with four alpha-helices packed onto it to create a …

Folding and stability of the aquaglyceroporin GlpF: Implications for human aqua(glycero)porin diseases

2015

AbstractAquaporins are highly selective polytopic transmembrane channel proteins that facilitate the permeation of water across cellular membranes in a large diversity of organisms. Defects in aquaporin function are associated with common diseases, such as nephrogenic diabetes insipidus, congenital cataract and certain types of cancer. In general, aquaporins have a highly conserved structure; from prokaryotes to humans. The conserved structure, together with structural dynamics and the structural framework for substrate selectivity is discussed. The folding pathway of aquaporins has been a topic of several studies in recent years. These studies revealed that a conserved protein structure ca…

Morphology, mechanical properties and thermal degradation kinetics of PMMA-zirconia nanocomposites prepared by melt compounding

2012

Zirconia nanoparticles were synthesized by means of a sol-gel method and embedded in poly(methyl methacrylate) (PMMA) by melt compounding. The zirconia was well dispersed in the PMMA matrix, with only a few clusters, especially for the highest investigated zirconia content. NMR results showed heteronuclear dipolar interactions involving the carbons and the surrounding hydrogen nuclei. The effect of the amount of zirconia, in the range of 1–5!wt%, on the thermomechanical properties and thermal degradation kinetics of PMMA was also investigated by means of dynamic mechanical analysis (DMA), thermogravimetric analyses (TGA), and Fourier-transform infrared spectroscopy (FTIR). The presenc…

Practices of development assistance and climate change mitigation in reshaping the Mozambican REDD+ strategy

2020

ABSTRACTThis paper studies how the practices of climate change governance and development assistance have reshaped the Reducing Emissions from Deforestation and Forest Degradation (REDD) process in Mozambique. We look at how the original goals of the Mozambican REDD+ strategy changed in the interplay of different governance-related practices, both those originating locally and nationally, and those coming from international organisations. The paper is based on the frameworks of multilevel governance and practice theory. We identify six combinations of practices that are relevant in the REDD+ programmes and projects. Three of them are incorporated in the general idea of sustainability, inclu…

Comparison of differences in resolution and sources of controlling factors for gully erosion susceptibility mapping

2018

Abstract Gully erosion has been identified as an important soil degradation process and sediment source, especially in arid and semiarid areas. Thus, it is useful to identify the spatial occurrence of this form of water erosion in the landscape and the most vulnerable areas. In this study, we explored the effects of different pixel sizes on some controlling factors extracted from a digital elevation model and remote sensing data when producing a gully erosion susceptibility map (GESM) of Ekbatan Dam Basin, Hamadan, Iran. An inventory map of the gully landforms was prepared based on global positioning system routes of the gullies, extensive field surveys, and visual interpretations of satell…

The use of vegetation as a natural strategy for landfill restoration

2018

Long-term no-tillage application increases soil organic carbon, nitrous oxide emissions and faba bean (Vicia faba L.) yields under rain-fed Mediterra…

2018

The introduction of legumes into crop sequences and the reduction of tillage intensity are both proposed as agronomic practices to mitigate the soil degradation and negative impact of agriculture on the environment. However, the joint effects of these practices on nitrous oxide (NO) and ammonia (NH) emissions from soil remain unclear, particularly concerning semiarid Mediterranean areas. In the frame of a long-term field experiment (23 years), a 2-year study was performed on the faba bean (Vicia faba L.) to evaluate the effects of the long-term use of no tillage (NT) compared to conventional tillage (CT) on yield and NO and NH emissions from a Vertisol in a semiarid Mediterranean environmen…

Nitric oxide synthase inhibition and oxidative stress in cardiovascular diseases: Possible therapeutic targets?

2013

International audience; Nitric oxide (• NO) is synthetized enzymatically from L-arginine (L-Arg) by three NO synthase isoforms, iNOS, eNOS and nNOS. The synthesis of NO is selectively inhibited by guanidino-substituted analogs of L-Arg or methylarginines such as asymmetric dimethylarginine (ADMA), which results from protein degradation in cells. Many disease states, including cardiovascular diseases and diabetes, are associated with increased plasma levels of ADMA. The N-terminal catalytic domain of these NOS isoforms binds the heme prosthetic group as well as the redox cofactor, tetrahydrobiopterin (BH 4) associated with a regulatory protein, calmodulin (CaM). The enzymatic activity of NOS…

Thermomechanical degradation of polyethylene/polyamide 6 blend-clay nanocomposites

2014

Thermomechanical degradation of PP based nanocomposites filled with graphene nanoplatelets

2018

Graphitic nanofillers have extensively used to prepare nanocomposites based on both conventional petroleum based plastics and bio-based polymers . Among them, graphene or graphite nanoplatelets (GnP), also called graphite nanosheets or nanoflakes, are a relatively new carbon nanomaterial composed of stacked 2D graphene sheets with outstanding electrical, thermal and mechanical properties. Indeed, by adding GnP, also at low filler concentration (< 5 wt.%), the mechanical, heat-resistance, thermal and electrical properties of the polymer matrix can surprisingly enhance due to unique properties of these nanofillers. However, the characteristics of these multiphase systems certainly depend o…