The molecular and electronic structures of Co(II)-substituted azurin have been investigated using several realistic models of the metal coordination sphere. The geometry of the models was optimized using the hybrid density functional B3LYP method and compared to the structures obtained for similar Cu(II) models. It is found that Co(II) prefers a distorted tetrahedral structure with four strong bon

Semiempirical calculations, based on the so-called angular overlap model, have been compared with ab initio methods (MP2) for the calculation of nuclear quadrupole interactions (NQI's) in cadmium complexes with biologically relevant ligands (H2O, OH-, cysteinate, carboxylate, and imidazole). The assumptions on which the semiempirical model is based have been tested and the comparison indicates tha

The relative energies of different coordination modes (bidentate, monodentate, syn, and anti) of a carboxylate group bound to a zinc ion have been studied by the density functional method B3LYP with large basis sets on realistic models of the active site of several zinc proteins. In positively charged four-coordinate complexes, the mono- and bidentate coordination modes have almost the same energy

Free energy perturbations have been performed on two blue copper proteins, plastocyanin and nitrite reductase. By changing the copper coordination geometry, force constants, and charges, we have estimated the maximum energy with which the proteins may distort the copper coordination sphere. By comparing this energy with the quantum chemical energy cost for the same perturbation on the isolated cop

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

Quantum chemical geometry optimisations have been performed on realistic models of the active site of myoglobin using density functional methods. The energy of the hydrogen bond between the distal histidine residue and CO or O2 has been estimated to be 8 kJ/mol and 32 kJ/mol, respectively. This 24 k J/mol energy difference accounts for most of the discrimination between CO and O2 by myoglobin (abo

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

Theoretical investigations of the structure and function of the blue copper proteins and the dimeric CuA site 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. We also comp

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 (

The purpose of this study was to investigate the adsorption mechanism in reversed-phase chromatography (RPC) of proteins and to develop a model for the effect of dual mobile phase modulators—a salt and an organic solvent—on this process. Two different adsorption mechanisms were considered: (1) pure association of a protein molecule and one or more ligands and (2) displacement of the organic modula

Laminar burning velocities of hydrocarbon blends of relevance to natural gas combustion, with addition of 0, 10, 35 and 50% hydrogen, were measured using the heat flux method. Hydrocarbon blends were methane (80%)/ethane (20%), methane (80%)/propane (20%) and methane (80%)/ethane (10%)/propane (10%), and in addition experiments were performed using pure methane as a fuel. For the first time it was

The survival rate after childhood cancer has improved markedly and today more than 80% of patients will survive. Many childhood cancer survivors suffer from late complications due to radiotherapy and chemotherapy. Survivors of Acute Lymphoblastic Leukaemia (ALL), treated with cranial radiotherapy, are at a particularly high risk of having endocrine complications. Purpose To illuminate childhood AL

The Gram-positive bacterium Enterococcus faecalis was investigated to test its ability to electrochemically communicate with electrodes. E. faecalis cells were successfully “wired” to gold electrodes through [Os(2,2′-bipyridine)2-poly(N-vinylimidazole)10Cl]2 +/+ redox polymer. Maximum current density achieved in response to 10 mM D-glucose was 18 ± 1 μA cm− 2. Control experiments without redox pol

Cohesive zone models based on classical interface-type formulations at finite deformations are subjected to fundamental physical principles such as thermodynamical consistency, balance equations and material frame indifference. However, these restraints are often ignored and in that respect such formulations are inconsistent. By way of contrast, a consistent cohesive zone framework suitable for th

The literature widely documents the negative liquidity impact of foreign participation in firms that permit high foreign institutional ownership. This paper employs a unique setting for the limited participation of qualified foreign institutional investors (QFIIs) in China's A-share market and examines how this impacts on stock liquidity in emerging markets. Contrary to the findings in the literat

Oil palm expansion results in a loss of biodiversity and associated ecosystem services. However, there are factors that influence the severity of these impacts and enhancing biodiversity within plantations is important. In the present study, we examined the role of epiphytes for supporting arthropod communities in oil palm plantations in Sumatra, Indonesia. We considered the effects of landscape c