Protoporphyrin

Protoporphyrins are tetrapyrroles containing the following side chains:

* methyl (4)
* propionic acid (2)
* vinyl (2)

Protoporphyrin IX is a biochemically widely used carrier molecule for divalent cations, e.g. together with iron (Fe 2+) the body of the heme- groupe of hemoglobin, myoglobin and many other heme- containing enzymes like cytochrome c and catalase is formed, complexed with magnesium-ions (Mg 2+) the main part of the Chlorophylls are formed.

The number (e.g. IX) indicates the position of different side cains, but the nomenclatur is historically grown and only in parts sytematically.

Protoporphyrin IX as a direct precursor of heme is accumulated by patients of erythropoietic protoporphyria, which is one of the genetic disorders of the biosynthesis of the heme -pathway. It causes a severe photosensivity against visible light.

The sensivity of protoporphyrin IX against light is also used as a therapy against different forms of cancer (photodynamic therapy, PDT).

Protoporphyrins are deposited in the shells of the eggs of some birds as a brown or red pigment, either as a ground colour or as spotting. This occurs in most passerine species, some ground-nesting non-passerines, such as waders, gulls, nightjars and sandgrouse, where it provides camouflage, and some parasitic cuckoos, which need to mimic their passerine hosts' eggs.

Protoporphyrins strengthen the egg shell, and are deposited where the shell is too thin as a result of calcium shortage. Spotting therefore tend to be heavier where the local soil is calcium-deficient, and in the eggs laid last in a clutch.

External links

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* - protoporphyrin IX