'Click chemistry' extended to live cells

BERKELEY, Calif., Oct. 31 (UPI) -- U.S. scientists reported click chemistry, a new technique for labeling biomolecules in vitro, has been extended to studies involving live cells.

Researchers at the Lawrence Berkeley National Laboratory and the University of California-Berkeley said their breakthrough opens the door for the live cell imaging of numerous biomolecules, including glycans, proteins and lipids.

Click chemistry is the popular term for a copper-catalyzed azide-alkyne reaction that makes it possible for certain chemical building blocks to "click" together in an irreversible linkage. The technique -- valuable for attaching small molecular probes to various biomolecules in a test tube or on fixed cells -- has not been used in live cells because of the cyotoxic copper catalyst.

"We’ve developed a copper-free variant of the click chemistry reaction that possesses comparable kinetics to the copper-catalyzed reaction and proceeds within minutes on live cells with no apparent toxicity," said Professor Carolyn Bertozzi, the study's principal investigator. "This is the first example of a click chemistry reaction that, like the copper-catalyzed version, proceeds at physiologically acceptable temperatures only without the toxic presence of copper."

Bertozzi and her colleagues report their research in the Proceedings of the National Academy of Sciences.