NEWS OF THE WEEK rell of California Institute of Technology in an accompanying commentary in Nature. Though nonnatural molecules, both the azide and the phosphine are tolerated within a living organism. And because of their foreignness, they react with nothing but each graduate students Jennifer A. other. NSTEAD OF MIMICKING A "That's the whole beauty of mouse with a test tube, Prescher and Danielle H. Dube chemistry professor Car- first inject anonnatural sugar, per- bioorthogonality" Bertozzi says. olyn R. Bertozzi and coworkers acetylated N-a-azidoacetylman- She likens the azide and phosphine at the University of California, nosamine, just under the skin of to abiological version ofunreactive Berkeley have successfully mim- a mouse. The mouse metabolizes argon. 'At least within the time icked a test tube with a mouse. the sugar, knocks off the acetyl frame we are talking about, the They carried out a simple organ- groups, and expresses it on the tip azide and the phosphine are inert to everything but each other." ofaglycanchain Bertozzi and Tirrell point to on the surface of A c O ^ H N '|A^N 3 some of its cells. the usefulness of this reaction in AcO The azido sugar studying changing cell surfaces in AcO' runs through the vivo, perhaps even in real time. ICell mouse's sialic Glycosylation patterns change as (Probe; 0 acid pathway and cells undergo major shifts—emCH3
