Editing Catecholamine (section)

===Degradation===

Catecholamines have a half-life of a few minutes when circulating in the blood. They can be degraded either by methylation by [[Catechol-O-methyl transferase|catechol-''O''-methyltransferases (COMT)]] or by deamination by [[Monoamine oxidase|monoamine oxidases (MAO)]].

[[MAOI]]s bind to MAO, thereby preventing it from breaking down catecholamines and other monoamines.
{{clear right}}

[[Catabolism]] of catecholamines is mediated by two main enzymes: catechol-''O''-methyltransferase (COMT) which is present in the synaptic cleft and cytosol of the cell and monoamine oxidase (MAO) which is located in the mitochondrial membrane. Both enzymes require cofactors: COMT uses [[Magnesium in biology|Mg<sup>2+</sup>]] as a cofactor while MAO uses [[Flavin adenine dinucleotide|FAD]]. The first step of the catabolic process is mediated by either MAO or COMT which depends on the tissue and location of catecholamines (for example degradation of catecholamines in the synaptic cleft is mediated by COMT because MAO is a mitochondrial enzyme). The next catabolic steps in the pathway involve [[alcohol dehydrogenase]], [[aldehyde dehydrogenase]] and [[aldehyde reductase]]. The end product of epinephrine and norepinephrine is [[vanillylmandelic acid|vanillylmandelic acid (VMA)]] which is excreted in the [[urine]]. Dopamine catabolism leads to the production of [[homovanillic acid|homovanillic acid (HVA)]].<ref>{{cite journal|last1=Eisenhofer|first1=G.|last2=Kopin|first2=I. J.|last3=Goldstein|first3=D. S.|s2cid=12825309|title=Catecholamine metabolism: a contemporary view with implications for physiology and medicine|journal= Pharmacological Reviews|date=2004|volume=3|issue=56|pages=331–349|pmid=15317907|doi=10.1124/pr.56.3.1}}</ref>