© Alfred Pasieka Photo Researchers, Inc.
Gadget freaks love to "mod" their toys, and protein engineers are no exception. Just as people have found ways to trick-out their iPods, protein engineers have devised strategies to "tune up" enzymes, figuring out how they work and conferring new properties in the bargain.
Until recently, though, researchers were limited to the 20 naturally occurring amino acids and site-directed mutagenesis. But advances in chemical biology and genetics are providing access to the much larger realm of "unnatural" amino acids – those that can be chemically synthesized but seldom or never occur in nature.
"The potential for adding new properties is endless," says Yi Lu, who studies engineered metalloproteins at the University of Illinois at Urbana-Champaign. Researchers are using amino acid analogs to tease out the roles of individual residues in protein function, incorporate fluorescent labels for protein-trafficking studies, add photoactivatable crosslinkers for protein-protein interaction ...
