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Optimization to low temperature activity in psychrophilic enzymes.

Struvay C, Feller G - Int J Mol Sci (2012)

Bottom Line: Most psychrophilic enzymes optimize a high activity at low temperature at the expense of substrate affinity, therefore reducing the free energy barrier of the transition state.In these naturally evolved enzymes, the optimization to low temperature activity is reached via destabilization of the structures bearing the active site or by destabilization of the whole molecule.This involves a reduction in the number and strength of all types of weak interactions or the disappearance of stability factors, resulting in improved dynamics of active site residues in the cold.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biochemistry, Centre for Protein Engineering, University of Liège, Institute of Chemistry B6a, B-4000 Liège-Sart Tilman, Belgium; E-Mail: cstruvay@ulg.ac.be.

ABSTRACT
Psychrophiles, i.e., organisms thriving permanently at near-zero temperatures, synthesize cold-active enzymes to sustain their cell cycle. These enzymes are already used in many biotechnological applications requiring high activity at mild temperatures or fast heat-inactivation rate. Most psychrophilic enzymes optimize a high activity at low temperature at the expense of substrate affinity, therefore reducing the free energy barrier of the transition state. Furthermore, a weak temperature dependence of activity ensures moderate reduction of the catalytic activity in the cold. In these naturally evolved enzymes, the optimization to low temperature activity is reached via destabilization of the structures bearing the active site or by destabilization of the whole molecule. This involves a reduction in the number and strength of all types of weak interactions or the disappearance of stability factors, resulting in improved dynamics of active site residues in the cold. Considering the subtle structural adjustments required for low temperature activity, directed evolution appears to be the most suitable methodology to engineer cold activity in biological catalysts.

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Related in: MedlinePlus

Temperature dependence of activity. The activity of psychrophilic (open symbols, blue lines) and mesophilic (closed symbols) enzymes recorded at various temperatures illustrates the main properties of cold-adapted enzymes: cold activity and heat lability. Left panel, -amylases; right panel, cellulases. Both psychrophilic enzymes are from the Antarctic bacterium Pseudoalteromonas haloplanktis. Adapted from [11,12].
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f1-ijms-13-11643: Temperature dependence of activity. The activity of psychrophilic (open symbols, blue lines) and mesophilic (closed symbols) enzymes recorded at various temperatures illustrates the main properties of cold-adapted enzymes: cold activity and heat lability. Left panel, -amylases; right panel, cellulases. Both psychrophilic enzymes are from the Antarctic bacterium Pseudoalteromonas haloplanktis. Adapted from [11,12].

Mentions: The effect of temperature on the activity of psychrophilic and mesophilic enzymes is illustrated in Figure 1. Equation 1 is only valid for the exponential rise of activity with temperature on the left limb of the curves. This figure reveals at least three basic features of cold-adaptation. (i) In order to compensate for the slow reaction rates at low temperatures, psychrophiles synthesize enzymes having an up to tenfold higher specific activity in this temperature range. This is in fact the main physiological adaptation to cold at the enzyme level; (ii) The temperature for apparent maximal activity for cold-active enzymes is shifted towards low temperatures, reflecting the weak stability of these proteins and their unfolding and inactivation at moderate temperatures; (iii) Finally, the adaptation to cold is not always perfect. It can be seen in Figure 1 (left panel) that the specific activity of the psychrophilic enzymes at low temperatures, although very high, remains lower than that of the mesophilic enzyme at 37 °C.


Optimization to low temperature activity in psychrophilic enzymes.

Struvay C, Feller G - Int J Mol Sci (2012)

Temperature dependence of activity. The activity of psychrophilic (open symbols, blue lines) and mesophilic (closed symbols) enzymes recorded at various temperatures illustrates the main properties of cold-adapted enzymes: cold activity and heat lability. Left panel, -amylases; right panel, cellulases. Both psychrophilic enzymes are from the Antarctic bacterium Pseudoalteromonas haloplanktis. Adapted from [11,12].
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3472767&req=5

f1-ijms-13-11643: Temperature dependence of activity. The activity of psychrophilic (open symbols, blue lines) and mesophilic (closed symbols) enzymes recorded at various temperatures illustrates the main properties of cold-adapted enzymes: cold activity and heat lability. Left panel, -amylases; right panel, cellulases. Both psychrophilic enzymes are from the Antarctic bacterium Pseudoalteromonas haloplanktis. Adapted from [11,12].
Mentions: The effect of temperature on the activity of psychrophilic and mesophilic enzymes is illustrated in Figure 1. Equation 1 is only valid for the exponential rise of activity with temperature on the left limb of the curves. This figure reveals at least three basic features of cold-adaptation. (i) In order to compensate for the slow reaction rates at low temperatures, psychrophiles synthesize enzymes having an up to tenfold higher specific activity in this temperature range. This is in fact the main physiological adaptation to cold at the enzyme level; (ii) The temperature for apparent maximal activity for cold-active enzymes is shifted towards low temperatures, reflecting the weak stability of these proteins and their unfolding and inactivation at moderate temperatures; (iii) Finally, the adaptation to cold is not always perfect. It can be seen in Figure 1 (left panel) that the specific activity of the psychrophilic enzymes at low temperatures, although very high, remains lower than that of the mesophilic enzyme at 37 °C.

Bottom Line: Most psychrophilic enzymes optimize a high activity at low temperature at the expense of substrate affinity, therefore reducing the free energy barrier of the transition state.In these naturally evolved enzymes, the optimization to low temperature activity is reached via destabilization of the structures bearing the active site or by destabilization of the whole molecule.This involves a reduction in the number and strength of all types of weak interactions or the disappearance of stability factors, resulting in improved dynamics of active site residues in the cold.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biochemistry, Centre for Protein Engineering, University of Liège, Institute of Chemistry B6a, B-4000 Liège-Sart Tilman, Belgium; E-Mail: cstruvay@ulg.ac.be.

ABSTRACT
Psychrophiles, i.e., organisms thriving permanently at near-zero temperatures, synthesize cold-active enzymes to sustain their cell cycle. These enzymes are already used in many biotechnological applications requiring high activity at mild temperatures or fast heat-inactivation rate. Most psychrophilic enzymes optimize a high activity at low temperature at the expense of substrate affinity, therefore reducing the free energy barrier of the transition state. Furthermore, a weak temperature dependence of activity ensures moderate reduction of the catalytic activity in the cold. In these naturally evolved enzymes, the optimization to low temperature activity is reached via destabilization of the structures bearing the active site or by destabilization of the whole molecule. This involves a reduction in the number and strength of all types of weak interactions or the disappearance of stability factors, resulting in improved dynamics of active site residues in the cold. Considering the subtle structural adjustments required for low temperature activity, directed evolution appears to be the most suitable methodology to engineer cold activity in biological catalysts.

Show MeSH
Related in: MedlinePlus