Porphyrins

1. PORPHYRINSPORPHYRINS

2. Synthesis of porphyrins occurs in Synthesis of porphyrins occurs in
animals for haem production and in animals for haem production and in
plants for chlorophyll production.plants for chlorophyll production.

3. STRUCTURESTRUCTURE
Porphyrins are cyclic tetrapyrroles in which the pyrrole rings, Porphyrins are cyclic tetrapyrroles in which the pyrrole rings,
conventionally designated as A, B, C and D, are linked through conventionally designated as A, B, C and D, are linked through
their carbon atoms by methene (–CH=) bridgestheir carbon atoms by methene (–CH=) bridges
**
..

4. Porphyrins emit intense red fluorescence when Porphyrins emit intense red fluorescence when
exposed to light at around 400 nm. Thus, exposed to light at around 400 nm. Thus,
spectrofluorometric methods provide very spectrofluorometric methods provide very
sensitive detection and quantification of sensitive detection and quantification of
porphyrins porphyrins
The porphyrin isomers differ in the arrangement The porphyrin isomers differ in the arrangement
of the side-chain substituents (e.g. acetyl and of the side-chain substituents (e.g. acetyl and
propionyl in uroporphyrins; methyl and propionyl propionyl in uroporphyrins; methyl and propionyl
in coproporphyrins) in coproporphyrins) **..

5. Porphyrins are differentiated by the kind and Porphyrins are differentiated by the kind and
order of substitutes occupying the 8 peripheral order of substitutes occupying the 8 peripheral
position of pyrole rings of porphyrins .position of pyrole rings of porphyrins .
Of many kinds of porphyrins found in nature, Of many kinds of porphyrins found in nature,
only uroporphyrin caproporphyrin and only uroporphyrin caproporphyrin and
protoporphyrin have clinical significance. protoporphyrin have clinical significance. **

6. SYNTHESIS SYNTHESIS **

7. In mammalian cells, haem synthesis occurs mostly in liver and
erythropoietictissues (the erythropoietic cells (80%) and the liver
parenchymal cells (20%))
The biosynthetic pathway starts in the mitochondrion and, after
passing through three cytoplasmic stages, re-enters the
mitochondrion for the final steps of haem formation.
Haemoproteins play very important roles in electron and oxygen
transport, in the activation of oxygen or hydrogen peroxide and,
finally, in hydrogen peroxide decomposition

8. **

14. REGULATION OF HAEM SYNTHESIS **
Regulation of haem biosynthesis in the liver

15. Retroinhibition of hepatic ALAS1 activity via a negative
feedback regulation mediated by the free intracellular
haem pool.

16. BIBLIOGRAPHY BIBLIOGRAPHY
* Puy, Hervé and Deybach, Jean-Charles. "* Puy, Hervé and Deybach, Jean-Charles. "Haem biosynthesis and Haem biosynthesis and
excretion of porphyrinsexcretion of porphyrins", [Documento en línea]. Gastrohep, online ", [Documento en línea]. Gastrohep, online
Resource for Gastroenterology, Hepatology and Endoscopy. Resource for Gastroenterology, Hepatology and Endoscopy.
Dirección URL: Dirección URL:
<http://www.gastrohep.com/ebooks/rodes/Rodes_2_3_10.pdf>. <http://www.gastrohep.com/ebooks/rodes/Rodes_2_3_10.pdf>.
** ** King,King, Michael W. Ph.D. Michael W. Ph.D. Iron, Heme and Porphyrin MetabolismIron, Heme and Porphyrin Metabolism, ,
[Documento en línea]. The Medical Biochemistry Page. Dirección [Documento en línea]. The Medical Biochemistry Page. Dirección
URL: <http://themedicalbiochemistrypage.org/heme-URL: <http://themedicalbiochemistrypage.org/heme-
porphyrin.html>.porphyrin.html>.