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Heme (American English), or haem (Commonwealth English, both pronounced /hi:m/ HEEM), is a ring-shaped iron-containing molecular component of hemoglobin, which is necessary to bind oxygen in the bloodstream. It is composed of four pyrrole rings with 2 vinyl and 2 propionic acid side chains. [1] Heme is biosynthesized in both the bone marrow and ...
HMOX1 (heme oxygenase 1 gene) is a human gene that encodes for the enzyme heme oxygenase 1 (EC 1.14.99.3). Heme oxygenase (abbreviated HMOX or HO) mediates the first step of heme catabolism, it cleaves heme to form biliverdin. The HMOX gene is located on the long (q) arm of chromosome 22 at position 12.3, from base pair 34,101,636 to base pair ...
CPOX is an enzyme involved in the sixth step of porphyrin metabolism it catalyses the oxidative decarboxylation of coproporphyrinogen III to proto-porphyrinogen IX in the haem and chlorophyll biosynthetic pathways. [5] [11] The protein is a homodimer containing two internally bound iron atoms per molecule of native protein. [12]
Physiologically, porphyrias are classified as liver or erythropoietic based on the sites of accumulation of heme precursors, either in the liver or in the bone marrow and red blood cells. [29] Deficiency in the enzymes of the porphyrin pathway leads to insufficient production of heme. Heme function plays a central role in cellular metabolism.
Heme is a major source of dietary iron in humans and other mammals, and its synthesis in the body is well understood, but heme pathways are not as well understood. It is likely that heme is tightly regulated for two reasons: the toxic nature of iron in cells, and the lack of a regulated excretory system for excess iron.
Summary of heme B biosynthesis—note that some reactions occur in the cytoplasm and some in the mitochondrion (yellow) Ferrochelatase catalyzes the insertion of ferrous iron into protoporphyrin IX in the heme biosynthesis pathway to form heme B. The enzyme is localized to the matrix-facing side of the inner mitochondrial membrane.
Heme A (or haem A) is a heme, a coordination complex consisting of a macrocyclic ligand called a porphyrin, chelating an iron atom. Heme A is a biomolecule and is produced naturally by many organisms. Heme A, often appears a dichroic green/red when in solution, is a structural relative of heme B, a component of hemoglobin, the red pigment in blood.
Aminolevulinic acid synthase (ALA synthase, ALAS, or delta-aminolevulinic acid synthase) is an enzyme (EC 2.3.1.37) that catalyzes the synthesis of δ-aminolevulinic acid (ALA) the first common precursor in the biosynthesis of all tetrapyrroles such as hemes, cobalamins and chlorophylls. [1]