Protoporphyrin IX

Source: Wikipedia, the free encyclopedia.
Protoporphyrin IX
Identifiers
3D model (
JSmol
)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.008.213 Edit this at Wikidata
EC Number
  • 209-033-7
251232
KEGG
UNII
  • InChI=1S/C34H34N4O4/c1-7-21-17(3)25-13-26-19(5)23(9-11-33(39)40)31(37-26)16-32-24(10-12-34(41)42)20(6)28(38-32)15-30-22(8-2)18(4)27(36-30)14-29(21)35-25/h7-8,13-16,35,38H,1-2,9-12H2,3-6H3,(H,39,40)(H,41,42)/b25-13-,26-13-,27-14-,28-15-,29-14-,30-15-,31-16-,32-16- checkY
    Key: KSFOVUSSGSKXFI-UJJXFSCMSA-N checkY
  • CC\1=C(/C/2=C/C3=N/C(=C\C4=C(C(=C(N4)/C=C\5/C(=C(C(=N5)/C=C1\N2)C=C)C)C=C)C)/C(=C3CCC(=O)O)C)CCC(=O)O
Properties
C34H34N4O4
Molar mass 562.658 g/mol
Density 1.27 g/cm3
Hazards
GHS labelling:[1]
GHS07: Exclamation mark
Warning
H315, H319, H335
P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P319, P321, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Protoporphyrin IX is an organic compound, classified as a porphyrin, that plays an important role in living organisms as a precursor to other critical compounds like heme (hemoglobin) and chlorophyll. It is a deeply colored solid that is not soluble in water. The name is often abbreviated as PPIX.

Protoporphyrin IX contains a

aromatic character. Protoporphyrin IX is essentially planar, except for the N-H bonds that are bent out of the plane of the rings, in opposite (trans) directions.[2]

Nomenclature

The general term protoporphyrin refers to porphine derivatives that have the outer hydrogen atoms in the four pyrrole rings replaced by other functional groups. The prefix proto often means 'first' in science nomenclature (such as carbon protoxide), hence Hans Fischer is thought to have coined the name protoporphyrin as the first class of porphyrins.[3] Fischer described iron-deprived heme becoming the "proto-" porphyrin, particularly in reference to Hugo Kammerer's porphyrin.[4][5] In modern times, 'proto-' specifies a porphyrin species bearing methyl, vinyl, and carboxyethyl/propionate side groups.[6]

methyl groups −CH3 (M), two vinyl groups −CH=CH2 (V), and two propionic acid groups −CH2−CH2−COOH (P). The suffix "IX" indicates that these chains occur in the circular order MV-MV-MP-PM around the outer cycle at the following respective positions: c2,c3-c7,c8-c12,c13-c17,c18.[7]

The methine bridges of PPIX are named alpha (c5), beta (c10), gamma (c15), and delta (c20). In the context of heme, metabolic biotransformation by heme oxygenase results in the selective opening of the alpha-methine bridge to form biliverdin/bilirubin. In this case, the resulting bilin carries the suffix IXα which indicates the parent molecule was protoporphyrin IX cleaved at the alpha position. Non-enzymatic oxidation may result in the ring opening at other bridge positions.[8] The use of Greek letters in this context originates from the pioneering work of Georg Barkan in 1932.[9]

Properties

  • When UV light is shone on the compound, it fluoresces with a bright red color.
  • It Is also the component in egg shells that give them their characteristic brown color.[10]

Natural occurrence

The compound is encountered in nature in the form of

cation. When complexed with an iron(II) (ferrous) cation Fe2+, the molecule is called heme. Hemes are prosthetic groups in some important proteins. These heme-containing proteins include hemoglobin, myoglobin, and cytochrome c. Complexes can also be formed with other metal ions, such as zinc.[11]

Biosynthesis

Main article: Porphyrin § Synthesis

The compound is synthesized from acyclic precursors via a mono-pyrrole (

oxidized to protoporphyrin IX.[11] The last step is mediated by the enzyme protoporphyrinogen oxidase
.

protoporphyrin IX synthesis from protoporphyrinogen-IX

Protoporphyrin IX is an important precursor to biologically essential prosthetic groups such as heme, cytochrome c, and chlorophylls. As a result, a number of organisms are able to synthesize this tetrapyrrole from basic precursors such as glycine and succinyl-CoA, or glutamic acid. Despite the wide range of organisms that synthesize protoporphyrin IX, the process is largely conserved from bacteria to mammals with a few distinct exceptions in higher plants.[12][13][14]

In the biosynthesis of those molecules, the metal cation is inserted into protoporphyrin IX by enzymes called chelatases. For example, ferrochelatase converts the compound into heme B (i.e. Fe-protoporphyrin IX or protoheme IX). In chlorophyll biosynthesis, the enzyme magnesium chelatase converts it into Mg-protoporphyrin IX.

Described metalloprotoporphyrin IX derivatives

Protoporphyrin IX reacts with iron salts in air to give the complex FeCl(PPIX).[15] Heme coordinated with chlorine is known as hemin. Many metals other than Fe form Heme-like complexes when coordinated to PPIX. Of particular interest are cobalt derivatives because they also function as oxygen carriers.[16] Other metals - nickel, tin, chromium - have been investigated for their therapeutic value.[17]

Palepron is the disodium salt of protoporphyrin IX.[18]

History

Laidlaw may have first isolated PPIX in 1904.[5]

Clinical Importance

Protoporphyrin IX florescence from 5-ALA administration is used in fluorescent-guided surgery of glioblastoma.[19][20]

See also

References

  1. ^ "protoporphyrin IX". pubchem.ncbi.nlm.nih.gov.
  2. PMID 19518
    .
  3. PMID 25484638
    .
  4. ^ Fischer, Hans (1930). "On haemin and the relationships between haemin and chlorophyll" (PDF). Nobel Prize.
  5. ^
    PMID 6993245
    .
  6. S2CID 226269267
    .
  7. ^
    PMID 3208761
    .
  8. ^ Berk, Paul D.; Berlin, Nathaniel I. (1977). International Symposium on Chemistry and Physiology of Bile Pigments. U.S. Department of Health, Education, and Welfare, Public Health Service, National Institutes of Health.
  9. S2CID 4073510
    .
  10. PMID 26588930
    .
  11. ^
    ISBN 978-0-470-04867-2
    .
  12. S2CID 9070849
    .
  13. PMID 3895052
    .
  14. PMID 20506125
    .
  15. ISBN 978-0-470-13251-7. {{cite book}}: |journal= ignored (help
    )
  16. doi:10.1016/S0022-0728(02)00722-2
    .
  17. S2CID 9223457
    .
  18. ^ PubChem. "Protoporphyrin disodium". pubchem.ncbi.nlm.nih.gov. Retrieved 2021-04-15.
  19. PMID 35624942
    .
  20. PMID 34212784
    .
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