You are using an unsupported browser. Please upgrade your browser to a newer version to get the best experience on Human Metabolome Database.
Record Information
Creation Date2006-08-16 13:51:54 UTC
Update Date2016-02-11 01:04:24 UTC
Secondary Accession NumbersNone
Metabolite Identification
Common NameCarbon monoxide
DescriptionCarbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. It is the product of the incomplete combustion of carbon-containing compounds, notably in internal-combustion engines. It consists of one carbon atom covalently bonded to one oxygen atom. It is a gas at room temperature. Carbon monoxide is a significantly toxic gas and is the most common type of fatal poisoning in many countries. Exposures can lead to significant toxicity of the central nervous system and heart. Carbon monoxide has a higher diffusion coefficient compared to oxygen and the only enzyme in the human body that produces carbon monoxide is heme oxygenase which is located in all cells and breaks down heme. Because it has a higher diffusion coefficient than oxygen the body easily gets rid of any CO made. When CO is not ventilated it binds to hemoglobin, which is the principal oxygen-carrying compound in blood; this produces a compound known as carboxyhemoglobin. The traditional belief is that carbon monoxide toxicity arises from the formation of carboxyhemoglobin, which decreases the oxygen-carrying capacity of the blood and inhibits the transport, delivery, and utilization of oxygen by the body. The affinity between hemoglobin and carbon monoxide is approximately 230 times stronger than the affinity between hemoglobin and oxygen so hemoglobin binds to carbon monoxide in preference to oxygen. Following poisoning, long-term sequelae often occur. Carbon monoxide can also have severe effects on the fetus of a pregnant woman. Despite its serious toxicity, CO is extremely useful and underpins much modern technology, being a precursor to a myriad of useful - even life-saving - products. Carbon monoxide, though thought of as a pollutant today, has always been present in the atmosphere, chiefly as a product of volcanic activity. It occurs dissolved in molten volcanic rock at high pressures in the earth's mantle. Carbon monoxide contents of volcanic gases vary from less than 0.01% to as much as 2% depending on the volcano. It also occurs naturally in bushfires. Because natural sources of carbon monoxide are so variable from year to year, it is extremely difficult to accurately measure natural emissions of the gas. (wikipedia).
Monoxide, carbonMeSH
Chemical FormulaCO
Average Molecular Weight28.0101
Monoisotopic Molecular Weight27.994914622
IUPAC NameNot Available
Traditional NameNot Available
CAS Registry NumberNot Available
InChI Identifier
Chemical Taxonomy
DescriptionThis compound belongs to the class of chemical entities known as homogeneous other non-metal compounds. These are inorganic non-metallic compounds in which the largest atom belongs to the class of 'other non-metals'.
KingdomChemical entities
Super ClassInorganic compounds
ClassHomogeneous non-metal compounds
Sub ClassHomogeneous other non-metal compounds
Direct ParentHomogeneous other non-metal compounds
Alternative ParentsNot Available
  • Homogeneous other non metal
Molecular FrameworkNot Available
External Descriptors
StatusDetected and Quantified
  • Endogenous
  • Component of Porphyrin and chlorophyll metabolism
ApplicationNot Available
Cellular locations
  • Cytoplasm
  • Extracellular
Physical Properties
Experimental Properties
Melting Point-56.5 °CNot Available
Boiling PointNot AvailableNot Available
Water Solubility1.48 mg/mL at 25 °CNot Available
LogP0.83HANSCH,C ET AL. (1995)
Predicted Properties
Water Solubility5.11 mg/mLALOGPS
Physiological Charge0ChemAxon
Hydrogen Acceptor Count0ChemAxon
Hydrogen Donor Count0ChemAxon
Polar Surface Area0 Å2ChemAxon
Rotatable Bond Count0ChemAxon
Refractivity26.23 m3·mol-1ChemAxon
Polarizability1.94 Å3ChemAxon
Number of Rings0ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Spectrum TypeDescriptionSplash Key
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, NegativeNot Available
MSMass Spectrum (Electron Ionization)splash10-004i-9000000000-dfbb2bd73fc3d527a340View in MoNA
Biological Properties
Cellular Locations
  • Cytoplasm
  • Extracellular
Biofluid Locations
  • Blood
Tissue LocationNot Available
Acute Intermittent PorphyriaSMP00344Not Available
Congenital Erythropoietic Porphyria (CEP) or Gunther DiseaseSMP00345Not Available
Hereditary Coproporphyria (HCP)SMP00342Not Available
Porphyria Variegata (PV)SMP00346Not Available
Porphyrin MetabolismSMP00024map00860
Normal Concentrations
BloodDetected and Quantified72.0 +/- 25.0 uMAdult (>18 years old)BothNormal
    • Geigy Scientific ...
Abnormal Concentrations
BloodDetected and Quantified350.0 +/- 178.0 uMAdult (>18 years old)BothSmoking
    • Geigy Scientific ...
Associated Disorders and Diseases
Disease References
  1. Geigy Scientific Tables, 8th Rev edition, pp. 165-177. Edited by C. Lentner, West Cadwell, N.J.: Medical education Div., Ciba-Geigy Corp., Basel, Switzerland c1981-1992.
Associated OMIM IDsNone
DrugBank IDNot Available
DrugBank Metabolite IDNot Available
Phenol Explorer Compound IDNot Available
Phenol Explorer Metabolite IDNot Available
FoodDB IDFDB022578
KNApSAcK IDNot Available
Chemspider ID275
KEGG Compound IDC00237
BioCyc IDNot Available
BiGG ID1749973
Wikipedia LinkCarbon monoxide
NuGOwiki LinkHMDB01361
Metagene LinkHMDB01361
METLIN IDNot Available
PubChem Compound281
ChEBI ID17245
Synthesis ReferenceIvanova, Svetlana; Pitchon, Veronique; Petit, Corinne. Application of the direct exchange method in the preparation of gold catalysts supported on different oxide materials. Journal of Molecular Catalysis A: Chemical (2006), 256(1-2), 278-283.
Material Safety Data Sheet (MSDS)Not Available
General ReferencesNot Available


General function:
Involved in heme oxygenase (decyclizing) activity
Specific function:
Heme oxygenase cleaves the heme ring at the alpha methene bridge to form biliverdin. Biliverdin is subsequently converted to bilirubin by biliverdin reductase. Under physiological conditions, the activity of heme oxygenase is highest in the spleen, where senescent erythrocytes are sequestrated and destroyed. Heme oxygenase 2 could be implicated in the production of carbon monoxide in brain where it could act as a neurotransmitter.
Gene Name:
Uniprot ID:
Molecular weight:
Hemoglobin + FADH + Oxygen → Globin + Biliverdin + Carbon monoxide + Fe3+ + FAD + Waterdetails
General function:
Involved in heme oxygenase (decyclizing) activity
Specific function:
Heme oxygenase cleaves the heme ring at the alpha methene bridge to form biliverdin. Biliverdin is subsequently converted to bilirubin by biliverdin reductase. Under physiological conditions, the activity of heme oxygenase is highest in the spleen, where senescent erythrocytes are sequestrated and destroyed.
Gene Name:
Uniprot ID:
Molecular weight:
Hemoglobin + FADH + Oxygen → Globin + Biliverdin + Carbon monoxide + Fe3+ + FAD + Waterdetails
General function:
Involved in monooxygenase activity
Specific function:
Cytochromes P450 are a group of heme-thiolate monooxygenases. This enzyme requires molecular oxygen and NADPH for the omega-hydroxylation of LTB4, a potent chemoattractant for polymorphonuclear leukocytes.
Gene Name:
Uniprot ID:
Molecular weight:
General function:
Involved in ion channel activity
Specific function:
Potassium channel activated by both membrane depolarization or increase in cytosolic Ca(2+) that mediates export of K(+). It is also activated by the concentration of cytosolic Mg(2+). Its activation dampens the excitatory events that elevate the cytosolic Ca(2+) concentration and/or depolarize the cell membrane. It therefore contributes to repolarization of the membrane potential. Plays a key role in controlling excitability in a number of systems, such as regulation of the contraction of smooth muscle, the tuning of hair cells in the cochlea, regulation of transmitter release, and innate immunity. In smooth muscles, its activation by high level of Ca(2+), caused by ryanodine receptors in the sarcoplasmic reticulum, regulates the membrane potential. In cochlea cells, its number and kinetic properties partly determine the characteristic frequency of each hair cell and thereby helps to establish a tonotopic map. Kinetics of KCNMA1 channels are determined by alternative splicing, phosphorylation status and its combination with modulating beta subunits. Highly sensitive to both iberiotoxin (IbTx) and charybdotoxin (CTX)
Gene Name:
Uniprot ID:
Molecular weight:
General function:
Involved in protein serine/threonine kinase activity
Specific function:
Mediates down-regulation of protein synthesis in response to various stress conditions by the phosphorylation of EIF2S1 at 'Ser-48' and 'Ser-51'. Protein synthesis is inhibited at the level of initiation
Gene Name:
Uniprot ID:
Molecular weight:
General function:
Involved in metal ion binding
Specific function:
Catalyzes the formation of formate and 2-keto-4-methylthiobutyrate (KMTB) from 1,2-dihydroxy-3-keto-5-methylthiopentene (DHK-MTPene). Also down-regulates cell migration mediated by MMP14. Necessary for hepatitis C virus replication in an otherwise non-permissive cell line.
Gene Name:
Uniprot ID:
Molecular weight:
1,2-Dihydroxy-3-keto-5-methylthiopentene + Oxygen → 3-Methylthiopropionic acid + Formic acid + Carbon monoxidedetails