Heme B
A Heme B is a heme (nonprotein, insoluble, Iron Protoporphyrin constituent of hemoglobin).
- Context:
- The COX-1 and COX-2 enzymes (cyclooxygenase) of recent fame, also contain heme B at one of two active sites..
- Example(s):
- Bradyrhizobium Japonicum http://www.uniprot.org/uniprot/Q03073
- PMID 8386371: “We report the discovery of a Bradyrhizobium japonicum gene cluster (fixNOQP ) in which mutations resulted in defective soybean root-nodule bacteroid development and symbiotic nitrogen fixation. The predicted, DNA-derived protein sequences suggested that FixN is a heme b and copper-binding oxidase subunit, FixO a monoheme cytochrome c, FixQ a polypeptide of 54 amino acids, and FixP a diheme cytochrome c and that they are all membrane-bound .”
- …
- Counter-Example(s):
- See: Plant Pigment, Hemoglobin, Myoglobin.
References
2020
- (Wikipedia, 2020) ⇒ https://en.wikipedia.org/wiki/Heme_B Retrieved:2020-10-9.
- Heme B or haem B (also known as protoheme IX) is the most abundant heme.Hemoglobin and myoglobin are examples of oxygen transport proteins that contain heme B. The peroxidase family of enzymes also contain heme B. The COX-1 and COX-2 enzymes (cyclooxygenase) of recent fame, also contain heme B at one of two active sites.
Generally, heme B is attached to the surrounding protein matrix (known as the apoprotein) through a single coordination bond between the heme iron and an amino-acid side-chain.
Both hemoglobin and myoglobin have a coordination bond to an evolutionarily-conserved histidine, while nitric oxide synthase and cytochrome P450 have a coordination bond to an evolutionarily-conserved cysteine bound to the iron center of heme B.
Since the iron in heme B containing proteins is bound to the four nitrogens of the porphyrin (forming a plane) and a single electron donating atom of the protein, the iron is often in a pentacoordinate state. When oxygen or the toxic carbon monoxide is bound the iron becomes hexacoordinated.
The correct structures of heme B and heme S were first elucidated by German chemist Hans Fischer.
- Heme B or haem B (also known as protoheme IX) is the most abundant heme.Hemoglobin and myoglobin are examples of oxygen transport proteins that contain heme B. The peroxidase family of enzymes also contain heme B. The COX-1 and COX-2 enzymes (cyclooxygenase) of recent fame, also contain heme B at one of two active sites.
2009
- Gene Ontology http://amigo.geneontology.org/cgi-bin/amigo/term-details.cgi?term=GO:0020037&session_id=2205amigo1247024466
- Accession:GO:0020037
- Ontology: molecular function
- Synonyms: exact: haem binding
- Definition
- Interacting selectively and non-covalently with heme, any compound of iron complexed in a porphyrin (tetrapyrrole) ring. [source: ChEBI:30413, GOC:ai]