Corrinoids are a group of compounds based on the skeleton of
corrin, a cyclic system containing four
pyrrole
Pyrrole is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4 H4 NH. It is a colorless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., ''N''-meth ...
rings similar to
porphyrins. These include compounds based on octadehydrocorrin, which has the trivial name
corrole.
The
cobalamins (
vitamin B12) are the best known members of the group. Other prominent examples include
cobyrinic acid and its hexaamide
cobyric acid;
cobinic acid and its hexaamide
cobinamide;
cobamic acid and
cobamide
Cobamide is a naturally occurring chemical compound containing cobalt in the corrinoid family of macrocyclic complexes. Cobamide works as a coenzyme
A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's ...
.
Compounds containing the "Cob-" prefix (''not'' corrin) are cobalt derivatives, and may include an
oxidation state
In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...
, as in "Cob(II)alamin". When cobalt is replaced by another metal or hydrogen, the name changes accordingly, as in
ferrobamic acid or
hydrogenobamic acid.
Reactions with cyanide
A solution of aquacyano-corrinoids, such as
cobalamin or
cobinamide, reacts with free cyanide in an aqueous sample. The binding of cyanide to the corrinoid cobalt center leads to a color change from orange to violet. Quantification of the cyanide content is feasible by
UV-vis spectroscopy. Absorption of the corrinoid on a solid phase, allows detection of cyanide even in colored samples, rendering this method appropriate for the analysis of cyanide in water, wastewater, blood, and food.
Furthermore, this technology is non-toxic and considerably less prone to interference than the pyridine-barbituric acid colorimetry method.
References
External links
*
"The Nomenclature of Corrinoids" at chem.qmul.ac.uk
Tetrapyrroles
*
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