Schoenheimer, Rudolf (1898–1941)

German-born US biochemist who introduced the use of isotopes as tracers to study biochemical processes in 1935.

Schoenheimer was born and educated in Berlin. In 1933 he emigrated to the USA, working at the University of Columbia. He committed suicide.

Schoenheimer used deuterium to replace some of the hydrogen atoms in molecules of fat, which he fed to laboratory animals.

On analysing the body fat of rats four days later, he found that about half of the labelled fat was being stored. This meant that, contrary to previous belief, there was a constant changeover in the body between stored fat and fat that was used.

Schoenheimer used the isotope nitrogen-15 (prepared by US chemist Harold Urey, also at Columbia) to label amino acids, the basic building blocks of proteins, and again found that component molecules of the body are continually being broken down and built up.

He summarized his findings in his book The Dynamical State of Bodily Constituents 1942.