1070-4272/05/7806-0981 + 2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 6, 2005, pp. 981!984. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 6, 2005,
Original Russian Text Copyright + 2005 by Shkutina, Stoyanova, Selemenev.
AND POLYMERIC MATERIALS
Specific Features of Glucoamylase Immobilization
by Adsorption on Fibrous Polyelectrolytes
I. V. Shkutina, O. F. Stoyanova, and V. F. Selemenev
Voronezh State University, Voronezh, Russia
Received March 2, 2005
Abstract-Some fundamental aspects of the immobilization of a hydrolytic enzyme glucoamylase via ad-
sorption on aminocarboxylic ion-exchangers with fibrous structure were considered. The sorption capacity
of amphoteric supports for the enzyme was studied in relation to the time of immobilization, concentration
of hydrogen ions and the protein, and the ionic form of a polyelectrolyte. The catalytic properties of free
and immobilized enzymes were compared.
Recently, the importance of reactions used to
obtain products from renewable vegetable raw ma-
terials has been steadily increasing. A stage in pro-
duction of glucose syrups widely used in food in-
dustry is saccharification of dextrinized starch, involv-
ing glucoamylase (a-1,4-glucanhydrolase, KF 22.214.171.124).
The presently arising increased interest in immobiliza-
tion of enzymes by supports of various kinds is due
to the large potentialities in use of bound enzymes
as specific and stable heterogeneous biocatalysts.
A study of the immobilization of enzymes is primari-
ly aimed to obtain data related to optimization of
the process, which presumes an effective combination
of the choice of a support with various conditions
and parameters of the system and provides that the ac-
tivity of the heterogeneous catalyst is preserved to
the maximum possible extent.
Among the existing immobilization methods, the ad-
sorption technique is distinguished by simplicity, re-
quires no preliminary modification of a support, uses
easily regenerated sorbents, and changes the structure
of the enzyme to a lesser extent, compared with the
case of covalent binding. In addition, of no less im-
portance is the economic expediency and ecological
safety of the method .
Despite that a large number of studies concerned
with glucoamylase immobilization have been reported,
the enzymatic process of hydrolytic amylolysis with
a hereterogeneous catalyst has not been implemented
Previously, glucoamylase has been immobilized on
a nonionogenic sorbent Stirosorb and granulated am-
photeric ion-exchangers . The present com-
munication reports the results obtained in glucoamy-
lase immobilization via adsorption on aminocarboxylic
fibrous ion-exchangers of the Fiban type. The choice
of sorbents as supports for enzyme immobilization is
due to the similarity of the structural components of
protein molecules and functional groups of polyelec-
trolytes. Use of fibers as supports is preferable in
some cases to application of sorbents in other forms.
Fiban fibers have a three-dimensional structure, highly
developed surface, good mechanical strength, and
chemical and osmotic resistance . The physical
form and properties of the biocatalyst obtained enable
its use in continuous processes, e.g., in column re-
actors. The enzymes incorporated into its structure
are protected from the inactivating influence of micro-
A hydrolytic enzyme glucoamylase from Aspergil-
lus awatori was studied. As supports for glucoamylase
immobilization served fibrous aminocarboxylic poly-
electrolytes K-3, K-5, and AK-22-1, which contain
, =NH, =N, and 3COOH as functional groups
. The ion-exchangers were prepared for immobiliza-
tion by selecting a fraction with a required grain size,
conditioning, and converting the ion-exchangers into
the necessary ionic form .