In amylase immobilization, one problem to be considered is
the large size of the substrate, the starch [6,21]. In these cases,
enzyme activity may decrease by different causes. As it occurs for
any enzyme, the activity may decrease if the enzyme areas relevant
for its activity become distorted [22]. But in this case, the enzyme
activity will also be hindered by two diffusion problems. First, the
large size of the substrate may produce diffusion limitations to the
entry of this large molecule to the pores of the biocatalyst [15].
Second, if the active center is oriented towards the support surface,
it will be unavailable for the substrate [14]. Moreover, sweet
potato beta amylase presents an additional problem for immobilization.
Crystallographic studies demonstrate that the enzyme is
a tetramers [23,24]. This means that immobilization of all enzyme
subunits will be convenient to prevent subunits dissociation, stabilized
also each monomer via multipoint covalent attachment, and
in any case, reducing the risks of final product contamination by
the enzyme [11].
In this study, amylase extracted from sweet potato was immobilized
on agarose beads activated following different protocols and
the best derivative was further characterized.