Search results for "Catalysis"

Long-chain fatty acyl-CoA esters induce lipase activation in the absence of a water-lipid interface.

2003

In most lipases a mobile element or lid domain covers the catalytic site of the enzyme and the lid opening event, which usually proceed at a lipid-water interface, is required to form the catalytically competent lipase. We report here a noticeable increase in activity of two fungal lipases assayed in aqueous solution in absence of any interface when adding submicellar concentrations of amphipathic physiological molecules like long-chain acyl-CoAs. The catalytic activity was dramatically dependent on the acyl chain length of the amphiphile and could be related with a lid-opening process. Our data support that lipase activation can be triggered in the absence of a well-defined interface, and …

Reactivity of Nickel(II) Porphyrins in oCVD Processes—Polymerisation, Intramolecular Cyclisation and Chlorination

2019

Abstract Oxidative chemical vapour deposition of (5,15‐diphenylporphyrinato)nickel(II) (NiDPP) with iron(III) chloride as oxidant yielded a conjugated poly(metalloporphyrin) as a highly coloured thin film, which is potentially useful for optoelectronic applications. This study clarified the reactive sites of the porphyrin monomer NiDPP by HRMS, UV/Vis/NIR spectroscopy, cyclic voltammetry and EPR spectroscopy in combination with quantum chemical calculations. Unsubstituted meso positions are essential for successful polymerisation, as demonstrated by varying the porphyrin meso substituent pattern from di‐ to tri‐ and tetraphenyl substitution. DFT calculations support the proposed radical oxi…

MicroRNA-Based Therapeutic Perspectives in Myotonic Dystrophy

2019

Myotonic dystrophy involves two types of chronically debilitating rare neuromuscular diseases: type 1 (DM1) and type 2 (DM2). Both share similarities in molecular cause, clinical signs, and symptoms with DM2 patients usually displaying milder phenotypes. It is well documented that key clinical symptoms in DM are associated with a strong mis-regulation of RNA metabolism observed in patient’s cells. This mis-regulation is triggered by two leading DM-linked events: the sequestration of Muscleblind-like proteins (MBNL) and the mis-regulation of the CUGBP RNA-Binding Protein Elav-Like Family Member 1 (CELF1) that cause significant alterations to their important functions in RNA processing. It ha…

Janus Micelles Induced by Olefin Metathesis

2008

A facile one-step procedure for hydrophobic modification and simultaneous TEM contrast enhancement via a regioselective olefin metathesis reaction using Grubbs' catalyst is presented. Polyether diblock copolymers were investigated, and both the chain ends of the hydrophilic and the hydrophobic block were hydrophobically modified. Modification of the hydrophilic block results in nonsymmetric supramolecular structures (Janus micelles) which self-assemble into larger hierarchically organized super-micelles.

Effects of differential relevance of external stimuli on heart rate under food deprivation

1972

Ss were deprived of food for 24 h, after which heart rate (HR) was recorded with food placed before the Ss and also after they had eaten it. It was predicted, according to Malmo’s interaction hypothesis, that HR in both situations would be higher than at a control level but that the increase after food ingestion would be greater than that found in the presence of visual cues. The results did not wholly support these predictions. Only after eating were significant HR increases found. Possible reasons for the discrepancies between findings in this area were discussed.

The onset of convection in a two-layered porous medium with anisotropic permeability

2019

We consider convection in a horizontal porous layer of uniform thickness which is heated from below and which is composed of two anisotropic sublayers with principal axes lying in the three coordinate directions. The aim is to determine criteria for the onset of convection by finding the critical Rayleigh number, wavenumber and roll orientation relative to the coordinate axes. The full set of nondimensional parameters has at least six members even when the sublayers are considered to be thermally isotropic, and therefore, we select some special cases in order to illuminate the type of qualitative behaviour which may be expected. One such case is where the anisotropic sublayers are identical…

Onset of convection in a porous rectangular channel with external heat transfer to upper and lower fluid environments

2012

Published version of an article in the journal: Transport in Porous Media. Also available from the publisher at: http://dx.doi.org/10.1007/s11242-012-0018-9 The conditions for the onset of convection in a horizontal rectangular channel filled with a fluid saturated porous medium are studied. The vertical sidewalls are assumed to be impermeable and adiabatic. The horizontal upper and lower boundary walls are considered as impermeable and subject to external heat transfer, modelled through a third-kind boundary condition on the temperature field. The external fluid environments above and below the channel, kept at different temperatures, provide the heating-from-below mechanism which may lead…

Two-Dimensional Modeling of a Flat-Plate Photocatalytic Reactor for Oxidation of Indoor Air Pollutants

2007

In this paper we present a two-dimensional (2-D) analysis of a narrow-slit, flat-plate, single-pass, flow-through photocatalytic reactor for air purification. The continuity equation for convection and diffusion in two dimensions, under un-steady-state conditions, was coupled with radiation field modeling and photocatalytic reaction kinetics to model the transient and steady-state behavior of the reactor. The model was applied to the photocatalytic oxidation of trichloroethylene (TCE) in humidified air streams under different experimental conditions. The kinetic parameters determined by a three-dimensional (3-D) computational fluid dynamics model of the reactor were used in the 2-D model si…

Novel Imidazolium Based Catalyst for the Chemical Fixation of Carbon Dioxide

2015

Strong Cooperativity and Loose Geometry between CUB Domains Are the Basis for Procollagen C-Proteinase Enhancer Activity

2009

Procollagen C-proteinase enhancers (PCPE-1 and -2) specifically activate bone morphogenetic protein-1 (BMP-1) and other members of the tolloid proteinase family during C-terminal processing of fibrillar collagen precursors. PCPEs consist of two CUB domains (CUB1 and CUB2) and one NTR domain separated by one short and one long linker. It was previously shown that PCPEs can strongly interact with procollagen molecules, but the exact mechanism by which they enhance BMP-1 activity remains largely unknown. Here, we used a series of deletion mutants of PCPE-1 and two chimeric constructs with repetitions of the same CUB domain to study the role of each domain and linker. Out of all the forms teste…