Effect of temperature and pressure on yeast invertase stability: a kinetic and conformational study.
Kinetics of the temperature- or pressure-induced denaturation of invertase from Saccharomyces cerevisiae were obtained in the temperature range 45-70 degrees C and in the pressure range 500-650 MPa. The investigation was done by measuring the residual activities after cooling or pressure release and the intrinsic fluorescence of aromatic amino-acids (tyrosine and tryptophan) upon excitation at 277 nm. The residual activity decreased exponentially as a function of time incubation according to a biphasic model either with pressure or temperature, whereas the fluorescence emission indicated a difference between these two parameters. When the enzyme was subjected to thermal treatment, the fluorescence of tyrosine and tryptophan decreased slowly, while after high-pressure treatment, these aromatic residues become more exposed to the aqueous solvent during unfolding, giving rise to a large decrease in fluorescence in the 330-340 nm region. Moreover, in the latter case, an enhancement of light scattering intensity showed changes in protein-protein interactions.
Cavaille
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INSA, Centre de Bioingénierie Gilbert Durand (URA CNRS 544, LA INRA), Toulouse, France.
Combes
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D001709:Biotechnology; D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D006874:Hydrostatic Pressure; D011487:Protein Conformation; D011489:Protein Denaturation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013050:Spectrometry, Fluorescence; D013696:Temperature; D043324:beta-Fructofuranosidase
D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase