Definition
ChEBI: A cyclic tetrapyrrole that consists of porphyrin bearing four methyl substituents at positions 3, 8, 13 and 17, two vinyl substituents at positions 7 and 12 and two 2-carboxyethyl substituents at positions 2 and 18. The parent of the class of protoporphyri
s.
Purification Methods
Protoporphyrin IX (3,18-divinyl-2,7,13,17-tetramethylporphin-8,12-dipropionic acid, ooporphyrin) [553-12-8] M 562.7, pKEst ~ 4.8. Protoporphyrin IX is purified by dissolving (4g) in 98-100% HCOOH (85mL), diluting with dry Et2O (700mL) and keeping at 0o overnight. The precipitate is collected and washed with Et2O, then H2O, and dried in a vacuum at 50o over P2O5. It crystallises from aqueous pyridine and from Et2O in monoclinic, brownish-yellow prisms. The UV max values in 25% HCl are 557.2, 582.2 and 602.4nm. It is freely soluble in ethanolic HCl, AcOH, CHCl3, and Et2O containing AcOH. It forms sparingly soluble diNa and diK salts. [Ramsey Biochemical Preparations 3 39 1953, UV: Holden Aust J. Exptl Biol and Med Sci 15 412 1937, Garnick J Biol Chem 175 333 1948, IR: Falk & Willis Aust J Sci Res [A] 4 579 1951, Beilstein 26 IV 3042.]
General Description
Protoporphyrin IX belongs to the porphyrin family, which are a class of tetrapyrroles. It is the iron-free form of hemin and amphiphilic in nature. It is the precursor of heme in its biosynthetic pathway.
Biochem/physiol Actions
Protoporphyrin IX?levels are elevated in?tumor?cells due to?metabolism anomalies?compared to normal?cells.
Enzyme inhibitor
This iiron-free, immediate precusor of heme (FWfree-acid = 562.67 g/mol; CAS 553-12-8; brownish-yellow solid; soluble in a number of organic solvents; disodium and dipotassium salts solublized in the presence of Tween 80) has lmax values in 25% HCl are 602.4, 582.2, and 557.2 nm. Protoporphryrin IX is also an activator of guanylate cyclase. See also Iron Protoporphyrin IX; Heme; Hemin Target(s): aminolevulinate aminotransferase; 5-aminolevulinate synthase; glutamate: glyoxylate aminotransferase; glutathione S-transferase; glyoxalase I, or lactoylglutathione lyase; guanylate cyclase; heme oxygenase; hydroxymethylbilane synthase, or porphobilinogen deaminase; nitric-oxide synthase; porphobilinogen synthase, or 5-aminolevulinate dehydratase; succinyl-CoA synthetase; tryptophan pyrrolase, or tryptophan 2,3-dioxygenase; and uroporphyrinogen decarboxylase.
Toxicity evaluation
protoporphyrin IX, is
highly toxic in the presence of light and molecular oxygen,
killing photosynthetic plants very quickly through the
generation of singlet oxygen.
