Immobilization of glucoamylase onto spacer-arm attached magnetic poly(methylmethacrylate) microspheres: characterization and application to a continuous flow reactor
My. Arica et al., Immobilization of glucoamylase onto spacer-arm attached magnetic poly(methylmethacrylate) microspheres: characterization and application to a continuous flow reactor, J MOL CAT B, 11(2-3), 2000, pp. 127-138
Magnetic poly(methylmethacrylate) microspheres (MPMMA) were prepared by the
solvent evaporation method and a 6-carbon spacer-arm (i.e. hexamethylene d
iamine, HMDA) was covalently attached by the reaction of carbonyl groups of
poly(methylmethacrylate). Glucoamylase was then covalently immobilized thr
ough the spacer-arm of the MPMMA microspheres by using either carbodiimide
(CDI) or cyanogen bromide (CNBr) as a coupling agent. The activity yield of
the immobilized glucoamylase was 57% for CDI coupling and 73% for CNBr cou
pling. Kinetic parameters were determined for both immobilized glucoamylase
preparations as well as for the free enzyme. The K-m values for immobilize
d glucoamylases CDI coupling (12.5 g l(-1) dextrin) and CNBr coupling (9.3
g l(-1) dextrin) were higher than that of the free enzyme (2.1 g l(-1) dext
rin) whereas V-max values were smaller for the immobilized glucoamylase pre
parations. The optimum operational temperature was 5 degreesC higher for bo
th immobilized preparations than that of the free enzyme. Operational, ther
mal and storage stabilities were found to be increased with immobilization.
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