Paul Zamecnik was born in Cleveland, Ohio. He went to Dartmouth College and graduated from Dartmouth Medical School in 1934. Although he trained to be a medical doctor, Zamecnik was always interested in science. He eventually decided to go into research because there was so much to discover. His interest in protein synthesis started with a question. In 1938, as an intern, Zamecnik was doing an autopsy on an obese woman. He wondered why there was fat when there should have been protein and muscle - no one knew the answer.
In 1939, Zamecnik approached Max Bergmann, a protein chemist at the Rockefeller Institute. He was hoping to get a job in Bergmann's lab so he could work on the problem of protein synthesis. Bergmann turned him down because Zamecnik was an M.D, not a Ph.D.
Zamecnik did get a fellowship to work with Kaj Linderstrøm-Lang at the Carlsberg Laboratory in Denmark. Linderstrøm-Lang was a leader in the field of protein chemistry and Zamecnik obtained enough training and experience that Bergmann gave him a job when he came back to the States.
Zamecnik didn't stay at the Rockefeller for long. He was offered a job at the Huntington Laboratory at the Massachusetts General Hospital in Boston. Here, he worked with Fritz Lipmann (1953 Nobel laureate) and used radioactive isotopes to prove that proteins were built from amino acids in a process requiring chemical energy - ATP. Zamecnik then became interested in how protein sequences were specified and to understand that he tried to isolate and identify all the components necessary for protein synthesis.
In 1952, Zamecnik was partially successful in that he made a cell-free extract from rat liver with which he was able to synthesize proteins from amino acids. In 1953, using this system, Zamecnik and Mahlon Hoagland showed that amino acids had to be energized, "activated," by ATP before they were incorporated into a peptide chain. Then in 1956, Hoagland followed up on an observation Zamecnik made earlier. Zamecnik noticed that low molecular weight RNA in the cell-free extract could be associated with radiolabeled amino acids. This led to the identification of tRNA - the adaptors Francis Crick predicted in his Central Dogma.
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Har Gobind Khorana, Marshall Nirenberg, and Robert Holley shared the 1968 Nobel Prize for Physiology and Medicine. Nirenberg and Khorana cracked the genetic code. Holley sequenced and deduced the structure of the first tRNA molecule.
Paul Zamecnik first developed the cell-free extract system, which Marshall Nirenberg adapted to decipher the genetic code. Paul Zamecnik and Mahlon Hoagland also isolated activated tRNA, the "adaptor" that shuttled amino acids to ribsomes for incorporati