covalent bonding, crosslinking,
graft co-polymerization and entrapment. Several different
variations based on the combination of these methods have been
developed (Cao, 2006; Hanefeld et al., 2009). Covalent immobilization
is usually associated with improved stability, and it is normally
preferred when envisaging applications in aqueous environment or
when denaturing factors exist, since the formation of multiple covalent
bonds between enzyme and carrier reduces conformational
flexibility and thermal vibrations preventing enzyme denaturation
and unfolding (Hanefeld et al., 2009).