Editing Histamine (section)

== Synthesis and metabolism ==
Histamine is derived from the [[decarboxylation]] of the [[amino acid]] [[histidine]], a reaction [[catalyst|catalyzed]] by the [[enzyme]] [[L-histidine decarboxylase|{{sc|L}}-histidine decarboxylase]]. It is a [[hydrophilic]] [[vasoactive]] [[amine]].

[[Image:Histidine decarboxylase.svg|thumb|center|433px|Conversion of [[histidine]] to histamine by [[histidine decarboxylase]]]]

Once formed, histamine is either stored or rapidly inactivated by its primary [[degradative enzyme]]s, [[histamine-N-methyltransferase|histamine-''N''-methyltransferase]] or [[diamine oxidase]]. In the central nervous system, histamine released into the [[synapse]]s is primarily broken down by histamine-''N''-methyltransferase, while in other tissues both enzymes may play a role. Several other enzymes, including [[MAO-B]] and [[ALDH2]], further process the immediate metabolites of histamine for excretion or recycling.

Bacteria also are capable of producing histamine using [[histidine decarboxylase]] enzymes unrelated to those found in animals.  A non-infectious form of foodborne disease, [[scombroid poisoning]], is due to histamine production by bacteria in spoiled food, particularly fish.  Fermented foods and beverages naturally contain small quantities of histamine due to a similar conversion performed by fermenting bacteria or yeasts.  [[Sake]] contains histamine in the 20–40&nbsp;mg/L range; [[wine]]s contain it in the 2–10&nbsp;mg/L range.<ref name="pmid17892274">{{cite journal | vauthors = Jayarajah CN, Skelley AM, Fortner AD, Mathies RA | title = Analysis of neuroactive amines in fermented beverages using a portable microchip capillary electrophoresis system | journal = Analytical Chemistry | volume = 79 | issue = 21 | pages = 8162–9 | date = November 2007 | pmid = 17892274 | doi = 10.1021/ac071306s |url= http://astrobiology.berkeley.edu/PDFs_articles/WineAnalysisAnalChem.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110719142418/http://astrobiology.berkeley.edu/PDFs_articles/WineAnalysisAnalChem.pdf | archive-date = 19 July 2011 }}</ref>