PORPHYRIN

Porphyrin

Porphyrins are a group of organic compounds, many naturally occurring. One of the best-known porphyrins is heme, the pigment in red blood cells; heme is a cofactor of the protein hemoglobin. Porphyrins are heterocyclic macrocycles composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges . Porphyrins are aromatic. That is, they obey Hückel's rule for aromaticity, possessing 4n+2 π electrons delocalized over the macrocycle. Thus porphyrin macrocycles are highly conjugated systems. As a consequence, they typically have very intense absorption bands in the visible region and may be deeply colored; the name ...

The above text is a snippet from Wikipedia: Porphyrin
and as such is available under the Creative Commons Attribution/Share-Alike License.

porphyrin

Noun

  1. Any of a class of heterocyclic compounds containing four pyrrole rings arranged in a square; they are important in biochemistry in a form with a metal atom in the central cavity (hemoglobin with iron, chlorophyll with magnesium, etc.).


The above text is a snippet from Wiktionary: porphyrin
and as such is available under the Creative Commons Attribution/Share-Alike License.

Need help with a clue?
Try your search in the crossword dictionary!