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

Heme is highly toxic; bilirubin, the breakdown product in mammals, is less so.

From Science Magazine • Jun. 8, 2023

“Desearía haber disfrutado un poco más ese momento. Heme aquí, frente a frente con De Niro todas las noches”.

From New York Times • Oct. 30, 2022

Heme, or soy leghemoglobin, is found most abundantly in animal flesh and is the catalyst for hundreds of chemical reactions that occur while a burger is cooking.

From Washington Post • Oct. 23, 2019

Heme has even greater affinity for nitric oxide than oxygen, and the body uses nitric oxide as a signaling molecule to control blood pressure.

From Scientific American • May 6, 2019

Two other Indian officers, Lieutenants Stroyan and Heme, also joined the expedition.

From Great African Travellers From Mungo Park to Livingstone and Stanley by Kingston, William Henry Giles