References of "Arpigny, J. L"
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See detailMolecular adaptations of enzymes from psychrophilic organisms
Feller, Georges ULg; Arpigny, J. L.; Narinx, E. et al

in Comparative Biochemistry and Physiology. A : Comparative Physiology (1997), 118(3), 495-499

The dominating adaptative character of enzymes from cold-evolving organisms is their high turnover number (k(cat)) and catalytic efficiency (k(cat)/K-m), which compensate for the reduction of chemical ... [more ▼]

The dominating adaptative character of enzymes from cold-evolving organisms is their high turnover number (k(cat)) and catalytic efficiency (k(cat)/K-m), which compensate for the reduction of chemical reaction rates inherent to low temperatures. This optimization of the catalytic parameters can originate from the highly flexible structure of these proteins providing enhanced abilities to undergo conformational changes during catalysis at low temperatures. Molecular modelling of the 3-D structure of cold-adapted enzymes reveals that only subtle modifications of their conformation can be related to the structural flexibility. The observed structural features include: 1) the reduction of the number of weak interactions involved in the folded state stability like salt bridges, weakly polar interactions between aromatic side chains, hydrogen bonding, arginine content and charge-dipole interactions in alpha-helices; 2) a lower hydrophobicity of the hydrophobic clusters forming the core of the protein; 3) deletion or substitution of proline residues in loops or turns connecting secondary structures; 4) improved solvent interactions with a hydrophilic surface via additional charged side chains; 5) the occurence of glycine clusters close to functional domains; and 6) a looser coordination of Ca2+ ions. No general rule from the molecular changes observed; rather, each enzyme adopts its own strategy by using one or a combination of these altered interactions. Enzymes from thermophiles reinforce the same type of interactions indicating that there is a continuity in the strategy of protein adaptation to temperature. (C) 1997 Elsevier Science Inc. [less ▲]

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See detailEnzymes from psychrophilic organisms
Feller, Georges ULg; Narinx, E.; Arpigny, J. L. et al

in FEMS Microbiology Reviews (1996), 18(2-3), 189-202

Psychrophilic organisms such as micro-organisms and other ectothermic species living in polar, deep- sea or any constantly low temperature environments, produce enzymes adapted to function at low ... [more ▼]

Psychrophilic organisms such as micro-organisms and other ectothermic species living in polar, deep- sea or any constantly low temperature environments, produce enzymes adapted to function at low temperature. These enzymes are characterized by a high catalytic efficiency at low and moderate temperatures but are rather thermolabile. Due to their high specific activity and their rapid inactivation at temperatures as low as 30 degrees C, they offer, along with the producing micro-organisms, a great potential in biotechnology. The molecular basis of the adaptation of cold cu-amylase, subtilisin, triose phosphate isomerase from Antarctic bacteria and of trypsin from fish living in North Atlantic and in Antarctic sea waters have been studied. The comparison of the 3D structures obtained either by protein modelling or by X-ray crystallography (North Atlantic trypsin) with those of their mesophilic counterparts indicates that the molecular changes tend to increase the flexibility of the structure by a weakening of the intramolecular interactions and by an increase of the interactions with the solvent. For each enzyme, the most appropriate strategy enabling it to accommodate the substrate at a low energy cost is selected. There is a price to pay in terms of thermosensibility because the selective pressure is essentially oriented towards the harmonization of the specific activity with ambient thermal conditions. However, as demonstrated by site-directed mutagenesis experiments carried out on the Antarctic subtilisin, the possibility remains to stabilize the structure of these enzymes without affecting their high catalytic efficiency. [less ▲]

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See detailTEMPERATURE-DEPENDENCE OF GROWTH, ENZYME-SECRETION AND ACTIVITY OF PSYCHROPHILIC ANTARCTIC BACTERIA
Feller, Georges ULg; Narinx, E.; Arpigny, J. L. et al

in Applied Microbiology & Biotechnology (1994), 41(4), 477-479

Five psychrophilic Antarctic bacteria have been selected for their capacity to secrete exoenzymes into culture medium. These strains are able to grow from 0 to about 25 degrees C. However, production of ... [more ▼]

Five psychrophilic Antarctic bacteria have been selected for their capacity to secrete exoenzymes into culture medium. These strains are able to grow from 0 to about 25 degrees C. However, production of lipase from Moraxella, alpha-amylase from Alteromonas haloplanctis, beta-lactamase from Psychrobacter immobilis and protease from Bacillus is maximal at temperatures close to that of their environment (-2 to 4 degrees C) and is strongly inhibited at higher temperatures. This thermal effect involves alterations in the secretory pathway in the upper range of temperatures, losses due to the enzyme thermal lability and in some cases to reduction in cell development. The apparent optimal activity temperature of these enzymes is between 30 and 40 degrees C, i.e. about 20 degrees C lower than that of their mesophilic counterparts. [less ▲]

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See detailLIPASES FROM PSYCHROTROPHIC ANTARCTIC BACTERIA
Feller, Georges ULg; Thiry, M.; Arpigny, J. L. et al

in FEMS Microbiology Letters (1990), 66(1-3), 239-243

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