Heme & biological oxidations
Porphyrin synthesis and turnover alongside enzyme systems that functionalize and conjugate endogenous or environmental compounds.
Heme synthesis alternates between mitochondrial and cytosolic reactions, beginning with aminolevulinate formation and ending with iron insertion into protoporphyrin IX. Its geography makes transport of intermediates part of the pathway logic.
Heme degradation opens the porphyrin ring and produces biliverdin, bilirubin and iron-handling consequences. Synthesis and breakdown are therefore connected by material identity but controlled through different enzyme systems.
Phase-I transformations introduce or expose functional groups through oxidation, reduction or hydrolysis. Phase-II enzymes transfer polar groups such as glucuronate, sulfate or glutathione. These labels organize reaction types; they are not a guarantee that Phase I always precedes Phase II for a given compound.
Ideas to carry into the map
- Heme synthesis crosses mitochondrial and cytosolic space.
- Functionalization and conjugation are reaction classes, not a mandatory sequence.
- Porphyrin turnover links ring chemistry to iron handling.
Pathways in this field note
Mitochondrial and cytosolic construction of heme followed by controlled degradation of the tetrapyrrole ring.
The broad source hierarchy for oxidative and conjugative transformations of diverse small molecules.
Oxidation, reduction and hydrolysis that expose or introduce functional groups.
Transfer of polar groups that changes the handling and elimination of many compounds.