References of "D'Amico, Salvino"
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See detailLife in the cold: psychrophilic enzymes
Collins, T.; Claverie, P.; D'Amico, Salvino ULg et al

in Recent Res. Devl. Proteins vol. 1 (2002)

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See detailStructural determinants of cold adaptation and stability in a psychrophilic alpha-amylase
D'Amico, Salvino ULg; Gerday, Charles ULg; Feller, Georges ULg

in Biologia (2002), 57(Suppl. 11), 213-219

The heat-labile alpha-amylase from an Antarctic bacterium is the largest known protein that unfolds reversibly according to a two-state transition, as shown by differential scanning calorimetry. Mutants ... [more ▼]

The heat-labile alpha-amylase from an Antarctic bacterium is the largest known protein that unfolds reversibly according to a two-state transition, as shown by differential scanning calorimetry. Mutants of this enzyme were produced, carrying intended additional weak interactions of a type found in thermostable alpha-amylases. It is shown that single amino acid side chain substitutions can significantly modify the melting point T-m, the calorimetric enthalpy DeltaH(cal), the cooperativity and reversibility of unfolding, the thermal inactivation rate constant, and the kinetic parameters k(cat) and K-m. Although all mutations were located far from the active site, their overall trend is to decrease both k(cat) and K-m, probably by making the molecule more rigid, but this protects mutants against thermal inactivation. [less ▲]

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See detailDid Psychrophilic Enzymes Really Win the Challenge?
Zecchinon, Laurent ULg; Claverie, P.; Collins, T. et al

in Extremophiles : Life Under Extreme Conditions (2001), 5(5), 313-21

Organisms living in permanently cold environments, which actually represent the greatest proportion of our planet, display at low temperatures metabolic fluxes comparable to those exhibited by mesophilic ... [more ▼]

Organisms living in permanently cold environments, which actually represent the greatest proportion of our planet, display at low temperatures metabolic fluxes comparable to those exhibited by mesophilic organisms at moderate temperatures. They produce cold-evolved enzymes partially able to cope with the reduction in chemical reaction rates and the increased viscosity of the medium induced by low temperatures. In most cases, the adaptation is achieved through a reduction in the activation energy, leading to a high catalytic efficiency, which possibly originates from an increased flexibility of either a selected area of or the overall protein structure. This enhanced plasticity seems in return to be responsible for the weak thermal stability of cold enzymes. These particular properties render cold enzymes particularly useful in investigating the possible relationships existing between stability, flexibility, and specific activity and make them potentially unrivaled for numerous biotechnological tasks. In most cases, however, the adaptation appears to be far from being fully achieved. [less ▲]

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See detailStructural Determinants of Cold Adaptation and Stability in a Large Protein
D'Amico, Salvino ULg; Gerday, Charles ULg; Feller, Georges ULg

in Journal of Biological Chemistry (2001), 276(28), 25791-6

The heat-labile alpha-amylase from an antarctic bacterium is the largest known protein that unfolds reversibly according to a two-state transition as shown by differential scanning calorimetry. Mutants of ... [more ▼]

The heat-labile alpha-amylase from an antarctic bacterium is the largest known protein that unfolds reversibly according to a two-state transition as shown by differential scanning calorimetry. Mutants of this enzyme were produced, carrying additional weak interactions found in thermostable alpha-amylases. It is shown that single amino acid side chain substitutions can significantly modify the melting point T(m), the calorimetric enthalpy Delta H(cal), the cooperativity and reversibility of unfolding, the thermal inactivation rate constant, and the kinetic parameters k(cat) and K(m). The correlation between thermal inactivation and unfolding reversibility displayed by the mutants also shows that stabilizing interactions increase the frequency of side reactions during refolding, leading to intramolecular mismatches or aggregations typical of large proteins. Although all mutations were located far from the active site, their overall trend is to decrease both k(cat) and K(m) by rigidifying the molecule and to protect mutants against thermal inactivation. The effects of these mutations indicate that the cold-adapted alpha-amylase has lost a large number of weak interactions during evolution to reach the required conformational plasticity for catalysis at low temperatures, thereby producing an enzyme close to the lowest stability allowing maintenance of the native conformation. [less ▲]

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See detailCold-adapted enzymes: an unachieved symphony
D'Amico, Salvino ULg; Claverie, P.; Collins, T. et al

in Storey, K. B.; Storey, J. M. (Eds.) Cell and Molecular Responses to Stress vol.2. Protein adaptations and signal transduction, (2001)

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See detailCold-adapted enzymes
Georlette, D.; Bentahir, M.; Claverie, P. et al

in Bulte, J.; DeCuyper, M. (Eds.) Focus on Biotechnology – Physics and Chemistry Basis for Biotechnology (2001)

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See detailStructural Similarities and Evolutionary Relationships in Chloride-Dependent Alpha-Amylases
D'Amico, Salvino ULg; Gerday, Charles ULg; Feller, Georges ULg

in Gene (2000), 253(1), 95-105

The alpha-amylase sequences contained in databanks were screened for the presence of amino acid residues Arg195, Asn298 and Arg/Lys337 forming the chloride-binding site of several specialized alpha ... [more ▼]

The alpha-amylase sequences contained in databanks were screened for the presence of amino acid residues Arg195, Asn298 and Arg/Lys337 forming the chloride-binding site of several specialized alpha-amylases allosterically activated by this anion. This search provides 38 alpha-amylases potentially binding a chloride ion. All belong to animals, including mammals, birds, insects, acari, nematodes, molluscs, crustaceans and are also found in three extremophilic Gram-negative bacteria. An evolutionary distance tree based on complete amino acid sequences was constructed, revealing four distinct clusters of species. On the basis of multiple sequence alignment and homology modeling, invariable structural elements were defined, corresponding to the active site, the substrate binding site, the accessory binding sites, the Ca(2+) and Cl(-) binding sites, a protease-like catalytic triad and disulfide bonds. The sequence variations within functional elements allowed engineering strategies to be proposed, aimed at identifying and modifying the specificity, activity and stability of chloride-dependent alpha-amylases. [less ▲]

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See detailCold-Adapted Enzymes: From Fundamentals to Biotechnology
Gerday, Charles ULg; Aittaleb, Mohamed; Bentahir, Mostafa et al

in Trends in Biotechnology (2000), 18(3), 103-7

Psychrophilic enzymes produced by cold-adapted microorganisms display a high catalytic efficiency and are most often, if not always, associated with high thermosensitivity. Using X-ray crystallography ... [more ▼]

Psychrophilic enzymes produced by cold-adapted microorganisms display a high catalytic efficiency and are most often, if not always, associated with high thermosensitivity. Using X-ray crystallography, these properties are beginning to become understood, and the rules governing their adaptation to cold appear to be relatively diverse. The application of these enzymes offers considerable potential to the biotechnology industry, for example, in the detergent and food industries, for the production of fine chemicals and in bioremediation processes. [less ▲]

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See detailCharacterization of the C-Terminal Propeptide Involved in Bacterial Wall Spanning of Alpha-Amylase from the Psychrophile Alteromonas Haloplanctis
Feller, Georges ULg; D'Amico, Salvino ULg; Benotmane, A. M. et al

in Journal of Biological Chemistry (1998), 273(20), 12109-15

The antarctic psychrophile Alteromonas haloplanctis secretes a Ca2+- and Cl--dependent alpha-amylase. The nucleotide sequence of the amy gene and the amino acid sequences of the gene products indicate ... [more ▼]

The antarctic psychrophile Alteromonas haloplanctis secretes a Ca2+- and Cl--dependent alpha-amylase. The nucleotide sequence of the amy gene and the amino acid sequences of the gene products indicate that the alpha-amylase precursor is a preproenzyme composed by the signal peptide (24 residues), the mature alpha-amylase (453 residues, 49 kDa), and a long C-terminal propeptide or secretion helper (192 residues, 21 kDa). In cultures of the wild-type strain, the 70-kDa precursor is secreted at the mid-exponential phase and is cleaved by a nonspecific protease into the mature enzyme and the propeptide. The purified C-terminal propeptide displays several features common to beta-pleated transmembrane proteins. It has no intramolecular chaperone function because active alpha-amylase is expressed by Escherichia coli in the absence of the propeptide coding region. In E. coli, the 70-kDa precursor is directed toward the supernatant. When the alpha-amylase coding region is excised from the gene, the secretion helper can still promote its own membrane spanning. It can also accept a foreign passenger, as shown by the extracellular routing of a beta-lactamase-propeptide fusion protein. [less ▲]

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