Search results

Filter

Filetype

Your search for "*" yielded 531579 hits

On the regulatory significance of inhibitors acting on non‐equilibrium enzymes in the Calvin photosynthesis cycle

Control analyses and kinetic model studies have been performed in order to obtain quantitative information on the regulatory significance of 12 experimentally well‐documented inhibitory interactions of Calvin cycle intermediates with the four non‐equilibrium cycle enzymes. Evidence is presented to show that none of these interactions contributes significantly to the cycle flux control over the ran

The coordination chemistry of the catalytic zinc ion in alcohol dehydrogenase studied by ab initio quantum chemical calculations

The coordination chemistry of the zinc ion in the active site of alcohol dehydrogenase has been studied by the ab initio Hartree–Fock method. Geometry optimizations were performed using analytical gradients and basis sets of double‐zeta quality. Correlation effects were included at the MP2 level. The active site was modeled by Zn(HS)2XL(H2O)0–2, where X denotes ammonia or imidazole and L denotes w

Molecular dynamics simulations of alcohol dehydrogenase with a four‐ or five‐coordinate catalytic zinc ion

A detailed parameterization is presented of a zinc ion with one histidine and two cysteinate ligands, together with one or two water, hydroxide, aldehyde, alcohol, or alkoxide ligands. The parameterization is tailored for the active site of alcohol dehydrogenase and is obtained entirely from quantum chemical computations. The force‐field reproduces excellently the geometry of quantum chemically op

The coordination chemistry of the structural zinc ion in alcohol dehydrogenase studied by ab initio quantum chemical calculations

The coordination chemistry of the structural zinc ion in horse liver alcohol dehydrogenase has been examined by quantum chemical geometry optimisations. It is shown that all four cysteine ligands are deprotonated in the enzyme, not only two of them as has been suggested. The Zn-S bond lengths are very sensitive to the theoretical treatment; in vacuum they are predicted to be 15 pm longer than in t

The coordination of the catalytic zinc ion in alcohol dehydrogenase studied by combined quantum-chemical and molecular mechanics calculations

The coordination number of the catalytic zinc ion in alcohol dehydrogenase has been studied by integrated ab initio quantum-chemical and molecular mechanics geometry optimisations involving the whole enzyme. A four-coordinate active-site zinc ion is 100-200 kJ/mol more stable than a five-coordinate one, depending on the ligands. The only stable binding site for a fifth ligand at the zinc ion is op

Ab initio calculations of electric field gradients in cadmium complexes

Calculations of the electric field gradient (EFG) at the cadmium nucleus have been carried out on Cd2+ in the field of two point charges, CdF2, CdCl2, and CdF2Cl2 2- at the RHF, MPn (n = 2, 3, 4), and CCSD(T) levels of theory, in order to evaluate the effects of electron correlation, relativity, and basis set truncation. The EFG has furthermore been calculated in two large molecules (approximately

The active-site metal coordination geometry of cadmium-substituted alcohol dehydrogenase : A theoretical interpretation of perturbed angular correlation of γ-ray measurements

The structure of eleven complexes of cadmium-substituted alcohol dehydrogenase with or without coenzyme and with different non-protein cadmium ligands has been estimated by combined quantum chemical and molecular mechanical geometry optimisations. The geometry of the optimised complexes is similar to the crystal structure of cadmium-substituted alcohol dehydrogenase, indicating that the method beh

The influence of axial ligands on the reduction potential of blue copper proteins

The reduction potentials of blue copper sites vary between 180 and about 1000 mV. It has been suggested that the reason for this variation is that the proteins constrain the distance between the copper ion and its axial ligands to different values. We have tested this suggestion by performing density functional B3LYP calculations on realistic models of the blue copper proteins, including solvent e

On the role of strain in blue copper proteins

Theoretical investigations of the structure and function of the blue copper proteins are described. We have studied the optimum vacuum geometry of oxidised and reduced copper sites, the relative stability of trigonal and tetragonal Cu(II) structures, the relation between the structure and electronic spectra, the reorganisation energy, and reduction potentials. Our calculations give no support to t

A Tetra-Nitrato Complex of Platinum(II), Synthesis and Crystal Structure of K2[Pt(NO3)4].1/2H2O

K2[Pt(NO3)4]·1/2H2O was prepared from ca 0.4 M solutions of platinum(II) perchlorate in perchloric acid by addition of KHCO3 and KNO3. Its crystal structure was determined from X-ray intensity data collected with a CAD-4 diffractometer. Monochromatic MoKα-radiation was used. The space group is I4/m with Z = 4; a = 7.5277(4) and c = 20.470(3) Å. The refinement converged to R = 0.036. The structure K2[Pt(NO3)4]·Full-size image (

Divergence in stakeholders' preferences : Evidence from a choice experiment on forest landscapes preferences in Sweden

A great deal of biodiversity can be found in private forests, and protecting it requires taking into consideration the preferences of key stakeholders. In this study, we examine divergence in stakeholders' preferences for forest attributes across the general public, private non-industrial forest owners and public and private forest officials in Sweden by conducting a discrete choice experiment. Ou

Estrogen receptor β1 in diffuse large B-cell lymphoma growth and as a prognostic biomarker

Diffuse large B-cell lymphoma (DLBCL) shows a higher incidence in males versus females. Epidemiological studies have shown that female gender is a favorable prognostic factor, which may be explained by estrogens. Here we show that when grafting human DLBCL cells to immunocompromised mice, tumor growth in males is faster. When treating mice grafted with either germinal center or activated B-cell li

α-Pinene Autoxidation Products May Not Have Extremely Low Saturation Vapor Pressures Despite High O : C Ratios

COSMO-RS (conductor-like screening model for real solvents) and three different group-contribution methods were used to compute saturation (subcooled) liquid vapor pressures for 16 possible products of ozone-initiated α-pinene autoxidation, with elemental compositions C10H16O4-10 and C20H30O10-12. The saturation vapor pressures predicted by the different methods varied widely. COSMO-RS predicted r

Quality of Life Among People with Psychiatric Disabilities : Does Day Centre Attendance Make a Difference?

The purpose was to investigate (i) how people with psychiatric disabilities who attend day centres experience their quality of life (QoL) compared to non-attendees, (ii) differences in QoL between those who attend meeting place-oriented centres and those who attend work-oriented centres, (iii) possible correlates of QoL among day centre attendees. Ninety-three day centre attendees and 82 non-atten

Developing a practice guideline for the occupational health services by using a community of practice approach : A process evaluation of the development process

Background: One way to facilitate the translation of research into the occupational health service practice is through clinical practice guidelines. To increase the implementability of guidelines it is important to include the end-users in the development, for example by a community of practice approach. This paper describes the development of an occupational health practice guideline aimed at the

Strategy of interference-free atomic hydrogen detection in flames using femtosecond multi-photon laser-induced fluorescence

Hydrogen atoms are key species in combustion of hydrogen/hydrocarbon fuels. Interference-free detection of hydrogen atoms natively generated in flames using femtosecond laser-induced fluorescence (LIF) was investigated employing two colors, i.e., 243 nm and 486 nm, as excitation source: two-photon excitation followed by a relay one-photon excitation. This strategy was compared with another commonl

E-learning programs in oncology : A nationwide experience from 2005 to 2014

Background: E-learning is an established concept in oncological education and training. However, there seems to be a scarcity of long-term assessments of E-learning programs in oncology vis-á-vis their structural management and didactic value. This study presents descriptive, nationwide data from 2005 to 2014. E-learning oncology programs in chemotherapy, general oncology, pain management, palliat

A comparison of DCIP inversion software

Electrical resistivity tomography (ERT) is a commonly used geophysical method, which can conveniently be combined with measuring time-domain induced polarization. The combined measurement can be termed DCIP, and can be employed in a wide range of situations such as pre-investigations for construction, or contaminant monitoring to name a few. An integral part of a DCIP survey is the software used f