11. This enzyme participates in the metabolism of riboflavin, porphyrin and chlorophyll. 12. Porphyrins are an additional class of conjugated, heterocyclic macrocycles.13. An example of catalysts of this type is Sander s porphyrin trimer. 14. All samples to detect porphyrins must be handled properly. 15. This behaviour is parallel with that observed for the corresponding metallo-porphyrins . 16. Haematin inhibits the synthesis of porphyrin , and stimulates the synthesis of globin. 17. These differences confer physical properties that are distinct from both porphyrins and phthalocyanines. 18. Natural porphyrin molecules are shaped somewhat like doughnuts. 19. Each iron atom is surrounded by a little ring of amino acids called porphyrin . 20. Deficiency in the enzymes of the porphyrin pathway leads to insufficient production of heme.
