Enzyme and Microbial Technology, Vol.24, No.1-2, 96-103, 1999
Facile synthesis of artificial enzyme nano-environments via solid-phase chemistry of immobilized derivatives : Dramatic stabilization of penicillin acylase versus organic solvents
A method to generate a highly hydrophilic nano-environment surrounding immobilized enzymes [penicillin acylase (PGA)] has been developed. The enzyme was firstly multipoint immobilized on a highly activated support having an internal morphology composed by large hydrophilic surfaces (a). After irreversible enzyme immobilization, a high molecular weight polyamine molecule was further immobilized on the same support surface. In this way, all areas of the enzyme next to the support surface may become embedded in a hydrophilic environment (b); or the immobilized enzyme was modified with a high molecular weight poly-aldehydic polymer which also becomes a hydrophilic poly-hydroxyl macromolecule after borohydride reduction (c). The single application of each distinct (b or, c) modifications did not promote stabilizing effects on immobilized PGA; however, the combined effect of both consecutive modifications (the chemical modification of the coimmobilized enzyme-polyamine derivative) promoted a dramatic stabilization of PGA versus organic solvents associated with a minimal loss of catalytic activity. The stabilizing effect was higher when the enzyme was incubated with large and hydrophobic organic solvents; thus, the modified derivative retained 80% of activity relative to soluble enzyme, but it was 1,000-fold more stable than the unmodified one in the presence of 90% tetraglyme. A fairly complete embedding of the whole enzyme surface in a highly hydrophilic nano-environment seems to be achieved.
Keywords:MULTIPOINT COVALENT ATTACHMENT, DEXTRAN-DIALDEHYDE POLYMERS;ESCHERICHIA-COLI, CHEMICAL MODIFICATION, AGAROSE DERIVATIVES;CROSS-LINKING, ANTIBIOTICS, GELS