The first experiment which showed that fatty acids are oxidized in C2-units has been done by Georg Franz Knoop and been published 1904 as "Der Abbau aromatischer Fettsäuren im Tierkörper.". The paper in reference 1 states:
Georg Franz Knoop discovered fatty acid β-oxidation. In 1904, he
published his classical experiments using odd and even chain ω-phenyl
fatty acids such as ω-phenylvaleric acid and ω-phenylbutyric acid
(Knoop 1904). Knoop fed these compounds to dogs and analysed their
urine. In dogs that had been fed the odd chain fatty acids, he found
hippuric acid (conjugate of benzoic acid and glycine), whereas, the
dogs that had been fed even chain fatty acids excreted phenaceturic
acid (conjugate of phenylacetic acid and glycine). From this he
concluded that the metabolism of fatty acids proceeds by the
successive removal of two carbon fragments. The remaining fatty chain
had to contain a carboxylic acid. He postulated that oxidation took
place on the β carbon atom, an oxidation unknown to organic chemistry.
If the fatty acid chain has an uneven number of carbon atoms, the resulting propionyl-CoA is modified into succinyl-CoA which is then used by different processes.
During the breakdown of the chain, Acetyl-CoA groups are released (at the end of each step), which can then be further metabolized by the body. Acetyl-CoA is fed into the Krebs cycle and then oxidized.
- A general introduction to the biochemistry of mitochondrial fatty
- Fatty Acid Oxidation