Peptides and proteins have attracted scientific and technological interest largely because
of their intriguing properties as catalysts, receptors, signalling molecules, and
therapeutic agents. In attempts to understand and exploit these properties, protein engineering
has been used primarily to obtain precious proteins in increased quantities,
or to explore systematic alterations in protein sequence through site-directed mutagenesis.
Design of protein structures de novo ("from scratch") has attracted less attention,
and has been directed in the main toward studies of protein folding (Kamtekar et
al., 1993). Such studies represent a key element in the current vigorous investigation
of the connections between amino acid sequence and the three-dimensional structures
of isolated protein chains in aqueous solution. This chapter describes protein engineering
of quite another sort, in which the proteinacious nature of the product is less
important than its macromolecular character
