/his"ti deen', -din/, n. Biochem.an essential amino acid, C3H3N2CH2CH(NH2)COOH, that is a constituent of proteins and is important as the iron-binding site in hemoglobin.[1895-1900; HIST- + -ID3 + -INE2]
* * *One of the essential amino acids, first isolated in 1896.It occurs abundantly in hemoglobin and can be isolated from blood cells. It is used in medicine and biochemical research and as a dietary supplement and feed additive.
* * *an amino acid obtainable by hydrolysis of many proteins. A particularly rich source, hemoglobin (the oxygen-carrying pigment of red blood cells) yields about 8.5 percent by weight of histidine. First isolated in 1896 from various proteins, histidine is one of several so-called essential amino acids for human beings; they cannot synthesize it and require dietary sources. In microorganisms histidine is synthesized from the sugar ribose and the nucleotide adenosine triphosphate.histamine (q.v.), a compound involved in the physiological processes associated with allergic reactions, is formed in the human body by decarboxylation of histidine.
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