heme


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Related to heme: heme protein, Heme iron, Heme oxygenase

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 ?
Renal response to tissue injury: lessons from heme oxygenase-1 GeneAblation and expression.
Lipophilic free heme catalyzes the formation of active radicals and intercalates into plasma membranes.
The carbon monoxide latches on to hemoglobin and prevents heme from popping off and causing more trouble.
Acute intermittent porphyria is a rare genetic disease where mutations in the porphobilinogen deaminase (PBGD) gene, results in insufficient activity of a protein necessary for heme synthesis.
blood pressure regulation and platelet aggregation) are mediated via NO binding to the iron in the heme prosthetic group of guanylate cyclase, which markedly activates the enzyme and thereby increases the intracellular concentration of the second messenger cGMP [9,10].
9:15 Analysis of Heme Oxygenase in Sheepshead Minnows, Cyprinodon
In a recent study, the toxicity of heme in the colon was totally inhibited when spinach or an equal amount of purified chlorophyll was added to the diet of heme-fed rats, which seems to suggest that Mom was right in admonishing us to eat our spinach and green vegetables
Higher intakes of cholesterol, animal protein, and heme iron (from meat) were also associated with increased risk.
In fact, when preliminary results of this other study became available, the HEME investigators performed an interim analysis of their own data and found that MRI was detecting acute hemorrhages not seen on CT.
Pathogenic bacteria utilize heme as a source to obtain the iron necessary for their survival and ability to establish an infection.
This is especially important for irradiated beef color because the content of heme pigments in beef is about 10-fold of that found in light meats.