heme

American  

[heem] / him /

noun

Biochemistry.

1. a deep-red iron-containing blood pigment, C 34 H 32 N 4 O 4 Fe, obtained from hemoglobin.

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heme Scientific  

/ hēm /

1. The deep red, nonprotein, iron-containing component of hemoglobin that carries oxygen. Heme is a porphyrin with an iron atom at its center. One of the free valence electrons of the iron atom of heme is bound to the hemoglobin molecule, while the other is available for binding to an oxygen atom. A hemoglobin molecule contains four hemes. Chemical formula: C ₃₄ H ₃₂ FeN ₄ O ₄ .

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Etymology

Origin of heme

First recorded in 1920–25; shortened form of hematin

Compare meaning

How does heme compare to similar and commonly confused words? Explore the most common comparisons:

• heme vs. hemoglobin

Example Sentences

See Examples For:

heme

In addition, meat also contains compounds such as heme iron which may actually increase the formation of N-nitrosamines.

From Science Daily ● Jun. 8, 2026

If the crystals clump, they lose surface area needed to process more heme efficiently.

From Science Daily ● Mar. 19, 2026

Precision fermentation is not a new technique in the plant-based world: Impossible Foods brews plant-derived heme to make its fake meat bleed.

From Salon ● Aug. 19, 2024

The company’s burgers also contain a genetically modified plant-based version of heme, an iron-containing molecule that is a component of beef.

From Los Angeles Times ● May 31, 2024

Each of these leaves clasps, at its center, an iron-containing chemical named heme that can bind oxygen—a reaction distantly akin to a controlled form of rusting.

From "The Gene" by Siddhartha Mukherjee