Stability of biocatalysts
Andrés
Illanes
Escuela de Ingeniería Bioquímica
Universidad Católica de Valparaíso
Avenida Brasil 2147, Valparaíso, Chile
Tel: 56-32-273642 Fax 56-32-273803
E-mail: aillanes@ucv.cl
Keywords: Biocatalysis,
Biocatalyst, Enzyme inactivation, Enzyme stability, Stabilization
Financial Support: Fondecyt
Grants 1950966 and 1971029
Biocatalysts are inherently
labile; therefore their operational stability is of paramount importance
for any bioprocess. The problem of biocatalyst stability has been tackled
from different perspectives, which are reviewed in the present paper.
Inherently stable biocatalysts
are well appreciated and a systematic effort is being done in the search
of new organisms that harbor them. The potential of extremophiles has
recently been recognized. Moreover, cloning such termophilic genes into
more suitable mesophilic hosts is now at hand to produce stable biocatalysts.
Another approach is to use site-directed mutagenesis to code for more
stable proteins. A relevant number of actual industrial biocatalysts are
being produced using such genetic and protein engineering tools.
Operational stabilization of
biocatalysts is an alternative. Immobilized and crystallized biocatalysts
are stable forms already in use. Also engineering the reaction media can
contribute to biocatalyst stabilization. This is a key factor for using
enzymes in organic synthesis where non-aqueous media are mandatory or
at least highly desirable.
Bioreactor design requires
sound expressions to describe biocatalyst inactivation under operation
conditions. Unfortunately, most information has been gathered in non-reactive
situations, which poorly describe actual behavior. Models are proposed
to consider the presence of substrate and products on biocatalyst stability
and thus describe properly bioreactor performance.
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