Improving the properties of amylolytic enzymes by protein engineering

Abstract

Modifying the properties of enzymes and proteins has become a relatively routine practice in both the academic and the bioindustrial sectors since the first introduction of the concept in the late 70's to early 80s. The original tools of site-specific modification and three dimensional structural analysis based design have expanded to include regio-targeted mutagenesis, homology based recruitment of amino acid residues and in vivo and in vitro recombination of genes. The advent of PCR based methodologies for gene cloning and manipulation have greatly increased the ability to design altered proteins yet at the same time have made the process less time-consuming as well. Add to this the ability to introduce thousands, if not millions, of variations into existing proteins, the rapid development of robotic based handling and screening systems and one has the basis for a revolutionary excursion into protein design. Yet in spite of all this capability, the successful outcome of a commercial protein engineering project remains based in three quite simple fundamental principles. First, one must have a clear understanding of the real world application conditions under which an enzyme is used and how these conditions can define what actually constitutes an improvement in the performance of the enzyme. Second, one must be able to quantitate what the improved property can deliver in terms of process value to the customer. And third, but clearly not the least, one must understand the key commercial features which can expedite or hinder the actual commercialization of a new product. These three questions can be restated in non-scientific terms as: what does the customer need?; what value will this bring to the customer?; and how can the product be delivered to the customer so that value is recognized by all? These three questions will form the basis of the following discussion on engineering improved amylolytic enzymes to the starch industry.