Protoporfirinogen-oksidaza odgovorna je za sedmi korak u biosintezi protoporfirina IX. Ovaj porfirin je prekursor hemoglobina, nositelja kisika kod životinja i hlorofila, u biljkama. Enzim katalizira dehidrogenaciju (uklanjanje vodikovih atoma) protoporfirinogena IX (proizvod šestog koraka u proizvodnji hema), da bi se formirao protoporfirin IX. Jedan dodatni enzim mora modificirati protoporfirin IX, prije nego što postane hem. Inhibicija ovog enzima je strategija koja se koristi u određenim herbicidima.
UROS: uroporfirinogen III sintaza (kongenitalna eritropoetska porfirija)
Klinički značaj
Varijegatna porfirija ili šarolika porfirija, uzrokovana je mutacijama u genu PPOX. U PPOX genu identificirano je više od 100 mutacija koje mogu uzrokovati ovu porfiriju. Jedna od mutacija, zamjena aminokiselinetriptofana za arginin na poziciji 59 (takođe pisano kao Arg59Trp ili R59W), pronađena je u oko 95 posto južnoafričkih porodica sa šarolikom porfirijom. Mutacije u PPOX genu smanjuju aktivnost enzima kojeg proizvodi gen, omogućavajući nusproizvodima da se nagomilaju u tijelu. Ovo nakupljanje, u kombinaciji s negenetskim faktorima (kao što su određeni lijekovi, alkohol i dijeta), uzrokuje ovaj tip porfirije.
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Vansjski linkovi
PDBe-KB provides an overview of all the structure information available in the PDB for Human Protoporphyrinogen oxidase