Protein PCR with Chimeric "Tadpoles"

© 2005 Nature Publishing Group

DNA has its PCR, but no comparable method exists for high-sensitivity detection of proteins. Now, a new class of protein-DNA chimeras, dubbed "tadpoles," could fill that void.¹ "Call this PCR for proteins and other molecules," says coauthor Roger Brent of the Molecular Sciences Institute in Berkeley, Calif.

Tadpoles are chimeric molecules containing a DNA tail and a protein head. The head has affinity for a specific target molecule. The tail, containing a T7 promoter for run-off transcription and a region for PCR amplification, mediates detection.

In tests for biotin and anthrax toxin, tadpoles detected targets across a concentration range of more than 11 orders of magnitude. As few as 600 biotin molecules could be detected with 95% confidence; this sensitivity is one billion times greater than standard ELISA. Measurement takes as little as three hours.

"It potentially allows even modest-affinity aptamers to have...