Catalysis via Other Enzymes

The use of cell-free extracts to produce proteins has been known for a long time. Early work in this area has been reviewed [53-55]. However, it is much less common to isolate the enzymes, sometimes to purify them, and use them for in vitro production of proteins. A successful example is a publication by Fruton et al. [56], who demonstrated the action of dipeptidyl transferase as a polymerase. Using this enzyme, they made a number of oligopeptides. 

One relatively recent example is the cyanobacterial nitrogen reserve cyanophy-cin (multi-L-arginyl-poly-L-aspartic acid). This polymer is of interest because the oligo-arginyl polyaspartic acid may function as a biodegradable polyelectrolyte in selected applications. This polymer is synthesized in vivo by the enzyme 

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