Otto Heinrich Warburg

Green, red, and mixed shades of haemins are known. If magnesium is replaced by iron in chlorophyll, green haemins are obtained. Their colour is due to a strong band in the red which is already recognized in chlorophyll.

These studies resulted eventually in a complete sequence analysis of the complex from several species, and in the atomic resolution structure of the F catalytic domain of the enzyme from bovine mitochondria, giving new insights into how ATP is made in the biological world.