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Solvent effects on the catalytic activity of subtilisin suspended in compressed gases

✍ Scribed by Inês Borges de Carvalho; Teresa Corrêa de Sampaio; Susana Barreiros

Publisher
John Wiley and Sons
Year
2000
Tongue
English
Weight
648 KB
Volume
49
Category
Article
ISSN
0006-3592

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✦ Synopsis

We studied a model transesterification reaction catalyzed by subtilisin Carlsberg suspended in carbon dioxide, propane, and mixtures of these solvents under pressure. To account for solvent effects due to differences in water partitioning between the enzyme and the bulk solvents, we measured water sorption isotherms for the enzyme in each solvent. We measured catalytic activity as a function of enzyme hydration and obtained bell-shaped curves with maxima at the same enzyme hydration (12%) in all the solvents. However, the activity maxima were different in all media, being much higher in propane than in either COz or the mixtures with 50 and 10% COz. Considerations based on the solvation ability of the solvents did not offer an explanation for the differences in catalytic activity observed. Our results suggest that COz has a direct adverse effect on the catalytic activity of subtilisin. 0 1996

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