Man-made proteins could be more useful than real ones

Researchers have constructed a protein out of amino acids not found in natural proteins, discovering that they can form a complex, stable structure closely resembling a natural protein. Their findings could help scientists design drugs that look and act like real proteins but won't be degraded by enzymes or targeted by the immune system, as natural proteins are.

The researchers, led by Howard Hughes Medical Institute (HHMI) professor Alanna Schepartz, reported their findings in the 14 February 2007 issue of the Journal of the American Chemical Society, published in advance online on 19 January 2007. Schepartz and her coauthors, Douglas Daniels, James Petersson, and Jade Qiu, are all at Yale University. A story in the 5 February 2007 issue of Chemical & Engineering News spotlighted the research.

As an HHMI professor, Schepartz received a $1 million grant to find ways to infuse undergraduate teaching with the excitement of research. Several of her HHMI undergraduates synthesised â-amino acid monomers that were used to prepare the synthetic protein.

Schepartz and colleagues built the short protein, or peptide, from â-amino acids, which, although they exist in cells, are never found in ribosomally produced proteins. â-amino acids differ from the á-amino acids that compose natural proteins by the addition of a single chemical component - a methylene group - into the peptide backbone.

"The fundamental insight from this study is that â-peptides can assemble into structures that generally resemble natural proteins in shape and stability," Schepartz said. She added that their findings about the structure of the molecule that she and her colleagues synthesised will help scientists construct more elaborate â-peptide assemblies and ones that possess true biologic function.

Such â-peptides could also be designed as pharmaceuticals that would be more effective than natural protein drugs, because the enzymes that degrade natural proteins would not affect them.