Watching the production of new proteins in live cells

Researchers at Columbia University, in collaboration with biologists in Baylor College of Medicine, have made a significant step in understanding and imaging protein synthesis, pinpointing exactly where and when cells produce new proteins.

Min and colleagues' new technique harnesses deuterium (a heavier cousin of the normal hydrogen atom), which was first discovered by Harold Urey in 1932, also at Columbia University. When hydrogen is replaced by deuterium, the biochemical activities of amino acids change very little.

When added to growth media for culturing cells, these deuterium-labeled amino acids are incorporated by the natural cell machineries as the necessary building blocks for new protein production. Hence, only newly synthesized proteins by living cells will carry the special deuterium atoms connected to carbon atoms. The carbon-deuterium bonds vibrate at a distinct frequency, different from almost all natural chemical bonds existing inside cells.

The Columbia team utilized an emerging technique called stimulated Raman scattering (SRS) microscopy to target the unique vibrational motion of carbon-deuterium bonds carried by the newly synthesized proteins. They found that by quickly scanning a focused laser spot across the sample, point-by-point, SRS microscopy is capable of delivering location-dependent concentration maps of carbon-deuterium bonds inside living cells.