Corrin
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| Surname | Corrin | |||||||||
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| Molecular formula | C 19 H 22 N 4 | |||||||||
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| Molar mass | 306.41 g mol −1 | |||||||||
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | ||||||||||
Corrin is a heterocyclic ring system, related to the porphyrin ring in hemoglobin . It consists of four reduced pyrrole subunits ( tetrapyrrole ), which are connected on three sides by a −C (CH) = methine bridge and directly on one side. Compared to porphyrin, there is no methine bridge between two pyrroles.
The corrin ring structure is the central component in the cobalt- containing vitamin B 12 (cyanocobalamin). It has similar properties to the 18π aromatic porphyrin, but it is
- more agile,
- not as straight as porphyrin and
- With a missing methine bridge and missing double bonds, it does not have aromatic properties.
Corrinoids
Compounds that contain corrin as a basic structure are called corrinoids . Almost all natural, metal-containing corrinoids contain a central cobalt atom, whereas the related porphyrins can contain various metals (such as platinum , nickel , cobalt , copper , iron , zinc and magnesium ). Metal-free corrinoids were isolated from phototrophic bacteria. Corrinoids are only produced by microorganisms.
biosynthesis
The genus Propionibacterium synthesizes various corrinoids starting from 5-aminolevulinic acid ( 5-ALA ). This is dimerized to the porphobilinogen (PBG). Four PBG units are linked to form different uroporphyrinogens ( UPG I, II, III), which are methylated using the enzyme uroporphyrinogen-III-methyltransferase . Then, in a chain of approx. 30 reaction steps, UPG becomes a biologically active corrinoid such as the cobalamin . Many higher organisms such as vertebrates, some mollusks and a few crustaceans and insects synthesize the structurally related hemoglobin , which contains iron instead of cobalt, in a similar way ; they lack the ability to remove the methine bridge between the two pyrrole subunits that are directly linked in corrinoids.
See also
swell
- ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
- ↑ Entry on porphyrins. In: Römpp Online . Georg Thieme Verlag, accessed on July 8, 2012.
- ↑ Lena I. Vorobjeva: Propionibacteria. Springer, 1999, ISBN 0-7923-5884-8 , pp. 160-161; limited preview in Google Book search.