heme


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heme:

see coenzymecoenzyme
, any one of a group of relatively small organic molecules required for the catalytic function of certain enzymes. A coenzyme may either be attached by covalent bonds to a particular enzyme or exist freely in solution, but in either case it participates intimately in
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.

Heme

 

the nonprotein component (the so-called prosthetic group) and the coloring matter of hemoglobin.

Chemically, heme is a compound of protoporphyrin and divalent iron. In the vertebrate body heme is synthesized from simpler nitrogen compounds (glycine and succinate) and from ferritin, a reserve iron-protein complex present in the spleen, liver, and bone marrow. The heme isolated from the blood of various vertebrates always has the same structure:

Free heme readily oxidizes in air to hematin, in which the iron atom is trivalent. Many years of research on the structure of heme were rewarded by the synthesis in 1929 by H. Fischer of hemin, the hydrochloride of heme.

heme

[hēm]
(biochemistry)
C34H32O4N4Fe An iron-protoporphyrin complex associated with each polypeptide unit of hemoglobin.
References in periodicals archive ?
The skeleton has been reported to contain the blue pigment, biliverdin IX[alpha], which is formed by heme oxygenase (HO) during heme decomposition.
The prooxidant mechanism of NaCl is thought to include its ability to reduce antioxidant enzyme activities and to displace iron ions with sodium in the heme pigments providing free iron [29].
Heme is an essential component of proteins such as Hb and myoglobin where it functions in life-sustaining oxygen transport and storage, respectively.
Possible role of heme oxygenase and ferritin," Laboratory Investigation, vol.
Researchers soon discovered the heme molecule exhibits this redox function in a LiCIO4 electrolyte, but does not with lithium hexafluorophosphate (LiPF6).
Ortiz De Montellano, "Autocatalytic modification of the prosthetic heme of horseradish but not lactoperoxidase by thiocyanate oxidation products.
Maines, "Heme oxygenase: function, multiplicity, regulatory mechanisms, and clinical applications," The FASEB Journal, vol.
Renal response to tissue injury: lessons from heme oxygenase-1 GeneAblation and expression.
These defects cause the accumulation of neurotoxic heme intermediates aminolevulinic acid and porphobilinogen, with ALA believed to be the primary neurotoxic intermediate responsible for causing both attacks and ongoing symptoms between attacks.
Soy leghemoglobin, or "heme," is the ingredient that gives the Impossible Burger its essential meat-like flavor.
Heme gives the Impossible Burger the appearance, cooking aroma and taste of beef.