Tetrapyrroles

from Wikipedia, the free encyclopedia
The basic forms of the cyclic tetrapyrroles ( pyrrole , porphine , porphyrin , porphyrinogen )

Tetrapyrroles are chemical compounds that are composed of four pyrrole rings. Depending on the arrangement of these pyrrole rings, cyclic tetrapyrroles differ from linear tetrapyrroles.

Classification

Cyclic tetrapyrroles

Porphyrins refer to cyclic tetrapyrroles. This group includes all chlorophylls , all heme ( cofactors of some proteins such as those of hemoglobin , myoglobin and the cytochromes ), as well as catalases (special peroxidases ). In the corrins lacks a methine bridge in comparison to porphyrins between two pyrrole rings, characterized the two rings are connected directly. The cobalamins are among the most important representatives of the Corrine .

Linear tetrapyrroles

When cyclic tetrapyrroles and their complexes break down, linear tetrapyrroles are formed, the bile pigments to which z. B. bilirubin and biliverdin include. In some algal groups the bile pigments similar Tetrapyrroles occur which Phycobilins that for photosynthesis as a chromophore as a prosthetic group are bound to proteins that phycobiliproteins. Also in the construction of cyclic tetrapyrroles, a linear tetrapyrrole, the hydroxymethylbilane, is initially formed .

history

In chlorophyll , a magnesium cation is chelated by a derivatized porphyrin ring. For his discovery of the nature of chlorophyll, Hans Fischer (1881–1945) received the 1930 Nobel Prize in Chemistry . The tetrapyrrole ring forms the basic skeleton of heme, all porphyrins and chlorophyll.

Evidence of this and a slightly modified compounds in petroleum succeeded Alfred Treibs in the 1930 's. Tetrapyrroles can thus be regarded as the first biomarker in geological sample material.

See also

Web links

Individual evidence

  1. ^ Theophil Eicher , Siegfried Hauptmann , Andreas Speicher: The Chemistry of Heterocycles , Wiley-VCH, 2012, ISBN 978-3-527-32747-8 , pp. 551-558.