- Heme b
Chembox new
ImageFile = Heme.svg
ImageSize =
IUPACName =
OtherNames =
Section1 = Chembox Identifiers
CASNo = 14875-96-8
PubChem = 444098
SMILES =
MeSHName = Heme+b
Section2 = Chembox Properties
Formula = C34H32O4N4Fe
MolarMass = 616.487
Appearance =
Density =
MeltingPt =
BoilingPt =
Section3 = Chembox Hazards
Solubility =
MainHazards =
FlashPt =
Autoignition =Heme B is the most abundant
heme ; bothhemoglobin andmyoglobin are examples of oxygen transport proteins that contain heme B and theperoxidase family of enzymes also contain heme B. TheCOX-1 andCOX-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 andmyoglobin have a coordination bond to an evolutionary conservedhistidine , whileNitric oxide synthase andCytochrome P450 have a coordination bond to an evolutionary conservedcysteine 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 bound with oxygen or the toxin carbon monoxide the iron is hexacoordinated.
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