Improvement of enzyme activity, stability and selectivity via immobilization techniques

In spite of their excellent catalytic properties, enzyme properties have to be usually improved before their implementation at industrial scale (where many cycles of high yield processes are desired). Generally, soluble enzymes have to be immobilized to be reused for long times in industrial reactors and, in addition to that, some other critical enzyme properties have to be improved like stability, activity, inhibition by reaction products, selectivity towards non-natural substrates. Some strategies to improve these enzyme properties during the performance of tailor-made enzyme immobilization protocols are here reviewed. In this way, immobilized enzymes may also exhibit much better functional properties than the corresponding soluble enzymes by very simple immobilization protocols. For example, multipoint and multisubunit covalent immobilization improve the stability of monomeric or multimeric enzymes. Moreover, enantioselectivity of different enzymes (e.g., lipases) may be also dramatically improved (from E= 1 to >100) by performing different immobilization protocols of the same enzyme. In all cases, enzyme engineering via immobilization techniques is perfectly compatible with other chemical or biological approaches to improve enzyme functions and the final success depend on the availability of a wide battery of immobilization protocols. (C) 2007 Elsevier Inc. All rights reserved.