Temperature adaptations in psychrophilic, mesophilic and thermophilic chloride-dependent alpha-amylases.
The functional and structural adaptations to temperature have been addressed in homologous chloride-dependent α-amylases from a psychrophilic Antarctic bacterium, the ectothermic fruit fly, the homeothermic pig and from a thermophilic actinomycete. This series covers nearly all temperatures encountered by living organisms. We report a striking continuum in the functional properties of these enzymes coupled to their structural stability and related to the thermal regime of the source organism. In particular, thermal stability recorded by intrinsic fluorescence, circular dichroism and differential scanning calorimetry appears to be a compromise between the requirement for a stable native state and the proper structural dynamics to sustain the function at the environmental/physiological temperatures. The thermodependence of activity, the kinetic parameters, the activations parameters and fluorescence quenching support these activity-stability relationships in the investigated α-amylases.
Laboratory of Biochemistry, Center for Protein Engineering, University of Liège, B-4000 Liège-Sart Tilman, Belgium.
Alexandre
A
Cipolla
François
F
Delbrassine
Jean-Luc
JL
Da Lage
Georges
G
Feller
D000192:Actinomycetales / Q000201:enzymology* / Q000502:physiology; D000222:Adaptation, Physiological; D000818:Animals; D002712:Chlorides / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000502:physiology; D004789:Enzyme Activation; D004795:Enzyme Stability; D019791:Guanidine / Q000494:pharmacology; D011487:Protein Conformation; D058767:Protein Unfolding / Q000187:drug effects; D031161:Pseudoalteromonas / Q000201:enzymology* / Q000502:physiology; D013696:Temperature; D013816:Thermodynamics; D000516:alpha-Amylases / Q000737:chemistry / Q000378:metabolism*
D002712:Chlorides; D000516:alpha-Amylases; D019791:Guanidine