ABSTRACT
Organisms evolve enzyme systems determined to function optimally in their natural environment for survival purposes. However, the optimal enzyme system for chemical or food processes may require characteristics that might differ considerably from those found in nature. Therefore, the greatest opportunity for improvement lies in engineering the properties that have not been naturally selected. Site-specific mutagenesis enabled biochemists to induce structural modifications on the basis o f rational design factors and theoretically, no enzyme function or property is inaccessible to modification by this technology. Specific activ ity, pH stability, substrate-binding affinity, inhibition characteristics, are some properties which make potential targets for modification by site-specific mutagenesis. Moreover, the development over the past two decades o f the techniques o f genetic engineering offers a completely different approach to the selection o f industrial enzymes with suitable properties. The ability to manipulate and recombine DNA allowed a more focused approach to mutagenesis, and created the potential for the manipulation o f industrial microorganisms to synthesize valuable new enzymes or food ingredients. In parallel to protein engineering progress, biochemical engineering offered the alterna tive technology o f enzyme immobilization, which aimed to significant improvements o f process economics by reuse o f the enzymes. However, in anticipation o f a major role in industrial processing, an enormous amount o f research has been targeted at new immobilization techniques, matrices and chemistries. The development o f novel biocatalytic enzymes by directed evolution is a new and promising area. The number o f reactions catalyzed by biological enzyme mimics, like abzymes (catalytic antibodies), is growing fast and low efficiency problems are gradually overcome. Other mimics (artificial enzymes) are also constructed on nonpolypeptide chain backbones and designed in order to withstand extreme conditions without loss o f activity or conformational changes. The purpose o f this chapter is to briefly review the state o f the art and science o f the most important new technologies involved in food enzyme engineering in a comprehensive manner.
