Born 18 Mar 1911; died 26 Nov 1991 at age 80.

American #biochemist who pioneered the use of #radioactive and #stable #isotopes to #trace #chemical #pathways by which the body creates its own #materials, such as #blood. He discovered the #metabolic pathway by which the #cell #synthesizes #heme (the red substance in #haemoglobin), #vitamin B-12 and related compounds. In 1946, with David Rittenberg, to investigate the path of #glycine in the body, he ingested glycine labelled with atoms of the stable isotope #nitrogen-15, and his blood was analyzed for products containing the tracer #atoms. Hence they found glycine is used to synthesize the #pyrrole rings of #protoporphyrin. Further, he found that red blood cells had a lifespan of about 127 days, which led to understanding certain red blood cell diseases. He continued to study the mechanism of the intermediary metabolism of #aminoacids.