Enhancing
Catalytic Activity and Stability of Yeast
Alcohol Dehydrogenase by Encapsulation in Chitosan-Calcium Phosphate
Hybrid Beads
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Abstract
A kind
of calcium phosphate-mineralized chitosan beads (chitosan–CaP)
was prepared via a one-pot method by adding droplets of Ca<sup>2+</sup>-containing chitosan aqueous solution into phosphate-containing sodium
tripolyphosphate aqueous solution. The chitosan beads formed immediately
coupled with in situ precipitation of calcium phosphate on the surface.
The antiswelling properties of hybrid beads were greatly improved
with the swelling degree as low as 5%. The morphology of the resultant
chitosan–CaP hybrid beads was observed by scanning electron
microscopy (SEM). Yeast alcohol dehydrogenase (YADH) was encapsulated
in the hybrid beads with an about 40% lower enzyme leakage compared
with that in the pure chitosan beads. The optimal temperature and
pH value for enzymatic conversion catalyzed by YADH immobilized in
the chitosan–CaP beads were 30 °C and 7.0, respectively,
which were identical to those for free YADH. The immobilized YADH
displayed obviously higher thermal stability, pH stability, recycling
stability, and storage stability than the free YADH counterpart