References of "Maes, Dominique"
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See detailMETZOON : Development of a quantitative microbial risk assessment for human salmonellosis through household consumption of fresh minced pork méat in Belgium.
Bollaerts, Kaatje; Messens, Winy; Delhalle, Laurent ULg et al

in Risk Analysis : An Official Publication of the Society for Risk Analysis (2009), 29(6), 820-840

A quantitative microbial risk assessment according to the Codex Alimentarius Principles is conducted to evaluate the risk on human salmonellosis through household consumption of fresh minced pork meat in ... [more ▼]

A quantitative microbial risk assessment according to the Codex Alimentarius Principles is conducted to evaluate the risk on human salmonellosis through household consumption of fresh minced pork meat in Belgium. The quantitative exposure assessment is carried out by building a modular risk model, called the METZOON-model, which covers the pork production from farm to fork. In the METZOON-model, the food production pathway is split up in six consecutive modules: (1) primary production, (2) transport & lairage, (3) slaughterhouse, (4) post-processing, (5) distribution & storage and (6) preparation & consumption. All the modules are developed to resemble as closely as possible the Belgian situation making use of the available national data. Several statistical refinements and improved modeling techniques are proposed. The model produces highly realistic results. The baseline predicted number of annual salmonellosis cases is 20513 [st. dev. 9061.45]. The risk is estimated higher for the susceptible population [est. 4.713 × 10−5; st. dev. 1.466 × 10−5] compared to the normal population [est. 7.704 × 10−6; st. dev. 5.414 × 10−6] and is mainly due to cross contamination via cook’s hands and only for a small extent to undercooking. [less ▲]

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See detailKinetics and Thermodynamics of Glucose Isomerase Crystallization
Sleutel, Mike; Willaert, Ronnie; Gillespie, Christopher et al

in Crystal Growth & Design (2009), 9

A quantitative study using laser confocal microscopy combined with differential interference microscopy on the kinetics and thermodynamics of the crystallization of glucose isomerase is presented ... [more ▼]

A quantitative study using laser confocal microscopy combined with differential interference microscopy on the kinetics and thermodynamics of the crystallization of glucose isomerase is presented. Fundamental crystallization parameters are determined from the kinetics of step advancement and rates of two-dimensional (2D) nucleation. The ruling mass transfer pathway and accompanying activation barriers are discussed. In brief, the solubility exhibits normal temperature dependence and the crystallization enthalpy is the thermodynamic driving force. The diminishing entropic cost for higher PEG concentrations is attributed to water structuring and a decrease in water activity. The prominent step generation mechanism is homogeneous 2D nucleation for high supersaturations. At low driving forces 2D nucleation occurs on anomalously hyperactive sites and the step edge free energies for homogeneous and heterogeneous nucleation are determined. The number of nucleation centers for both mechanisms are estimated and from the density of nucleation centers we obtain for the activation barrier of adsorption ∼3.8 kJ mol-1. No step-step interaction is observed for interstep distances >70 nm. Theoretical fits of step velocity data suggest surface diffusion makes a non-negligible contribution to surface kinetics. From the temperature dependence of the step kinetic coefficient the activation barrier for crystallization was determined to be <22.4 kJ mol-1. [less ▲]

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See detailToward a Definition of X-ray Crystal Quality
Maes, Dominique; Evrard, Christine ULg; Gavira, Jose et al

in Crystal Growth & Design (2008), 8(12), 4284-4290

Crystal X-ray quality is usually evaluated by looking at data quality parameters such as (relative) Wilson B-factor, resolution, R-factors, signal-to-noise ratio, and others. As these parameters are ... [more ▼]

Crystal X-ray quality is usually evaluated by looking at data quality parameters such as (relative) Wilson B-factor, resolution, R-factors, signal-to-noise ratio, and others. As these parameters are correlated, most studies focus on one or two of them. As part of a study of the effects of microgravity on X-ray quality, full data sets of 35 ferritin crystals (17 PromISS-4 “space” crystals and 18 from the ground control) were collected. Sixty-three parameters commonly used as indicative of X-ray data quality taken from the output of the processing, scaling, and merging software packages were analyzed. This highly dimensional “quality parameter dataset” was reduced using a principal component analysis. About 78% of the variability in the data set could be explained with the first four principal components. A score-plot in this four-dimensional space clearly showed two tendencies, one for the crystals grown in space and one for the ground crystals. The differences between the two groups are observed irrespective of the software package. They can be attributed to the first principal component and reflect the superior quality of the space crystals. [less ▲]

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See detailThe crystal structure of triosephosphate isomerase (TIM) from Thermotoga maritima: a comparative thermostability structural analysis of ten different TIM structures
Maes, Dominique; Zeelen, Johan P.; Thanki, Narmada et al

in Proteins (1999), 37(3), 441-53

The molecular mechanisms that evolution has been employing to adapt to environmental temperatures are poorly understood. To gain some further insight into this subject we solved the crystal structure of ... [more ▼]

The molecular mechanisms that evolution has been employing to adapt to environmental temperatures are poorly understood. To gain some further insight into this subject we solved the crystal structure of triosephosphate isomerase (TIM) from the hyperthermophilic bacterium Thermotoga maritima (TmTIM). The enzyme is a tetramer, assembled as a dimer of dimers, suggesting that the tetrameric wild-type phosphoglycerate kinase PGK-TIM fusion protein consists of a core of two TIM dimers covalently linked to 4 PGK units. The crystal structure of TmTIM represents the most thermostable TIM presently known in its 3D-structure. It adds to a series of nine known TIM structures from a wide variety of organisms, spanning the range from psychrophiles to hyperthermophiles. Several properties believed to be involved in the adaptation to different temperatures were calculated and compared for all ten structures. No sequence preferences, correlated with thermal stability, were apparent from the amino acid composition or from the analysis of the loops and secondary structure elements of the ten TIMs. A common feature for both psychrophilic and T. maritima TIM is the large number of salt bridges compared with the number found in mesophilic TIMs. In the two thermophilic TIMs, the highest amount of accessible hydrophobic surface is buried during the folding and assembly process. [less ▲]

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See detailLys13 plays a crucial role in the functional adaptation of the thermophilic triose-phosphate isomerase from Bacillus stearothermophilus to high temperatures
Alvarez, Marco; Wouters, Johan; Maes, Dominique et al

in Journal of Biological Chemistry (1999), 274(27), 19181-7

The thermophilic triose-phosphate isomerases (TIMs) of Bacillus stearothermophilus (bTIM) and Thermotoga maritima (tTIM) have been found to possess a His12-Lys13 pair instead of the Asn12-Gly13 pair ... [more ▼]

The thermophilic triose-phosphate isomerases (TIMs) of Bacillus stearothermophilus (bTIM) and Thermotoga maritima (tTIM) have been found to possess a His12-Lys13 pair instead of the Asn12-Gly13 pair normally present in mesophilic TIMs. His12 in bTIM was proposed to prevent deamidation at high temperature, while the precise role of Lys13 is unknown. To investigate the role of the His12 and Lys13 pair in the enzyme's thermoadaptation, we reintroduced the "mesophilic residues" Asn and Gly into both thermophilic TIMs. Neither double mutant displayed diminished structural stability, but the bTIM double mutant showed drastically reduced catalytic activity. No similar behavior was observed with the tTIM double mutant, suggesting that the presence of the His12 and Lys13 cannot be systematically correlated to thermoadaptation in TIMs. We determined the crystal structure of the bTIM double mutant complexed with 2-phosphoglycolate to 2.4-A resolution. A molecular dynamics simulation showed that upon substitution of Lys13 to Gly an increase of the flexibility of loop 1 is observed, causing an incorrect orientation of the catalytic Lys10. This suggests that Lys13 in bTIM plays a crucial role in the functional adaptation of this enzyme to high temperature. Analysis of bTIM single mutants supports this assumption. [less ▲]

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See detailTriose-phosphate isomerase (TIM) of the psychrophilic bacterium Vibrio marinus. Kinetic and structural properties
Alvarez, Marco; Zeelen, Johan Ph; Mainfroid, Véronique et al

in Journal of Biological Chemistry (1998), 273(4), 2199-206

The purification and characterization of triose-phosphate isomerase from the psychrophilic bacterium Vibrio marinus (vTIM) is described. Crystal structures of the vTIM-sulfate complex and the vTIM-2 ... [more ▼]

The purification and characterization of triose-phosphate isomerase from the psychrophilic bacterium Vibrio marinus (vTIM) is described. Crystal structures of the vTIM-sulfate complex and the vTIM-2-phosphoglycolate complex (at a 2.7-A resolution) are also presented. The optimal growth temperature of Vibrio marinus is 15 degrees C. Stability studies show that vTIM is an unstable protein with a half-life of only 10 min at 25 degrees C. The vTIM sequence is most closely related to the sequence of Escherichia coli TIM (eTIM) (66% identity), and several unique structural features described for eTIM are also seen in vTIM, but eTIM is considerably more stable. The Td values of vTIM and eTIM, determined by calorimetric studies, are 41 and 54 degrees C, respectively. Amino acid sequence comparison reveals that vTIM has an alanine in loop 8 (at position 238), whereas all other TIM sequences known to date have a serine. The vTIM mutant A238S was produced and characterized. Compared with wild type, the catalytic efficiency of the A238S mutant is somewhat reduced, and its stability is considerably increased. [less ▲]

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