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Facile synthesis of artificial enzyme nano-environments via solid-phase chemistry of immobilized derivatives: Dramatic stabilization of penicillin acylase versus organic solvents

Abstract:

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. Copyright (C) 1999 Elsevier Science Inc.