heme
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Definition
Noun: A complex, red, iron-containing organic pigment (a porphyrin) that is the oxygen-binding component of hemoglobin in red blood cells and of myoglobin in muscle tissue. It is essential for oxygen transport and storage in vertebrates and some other organisms.
Usage
The word "heme" is used primarily in biochemistry, physiology, and medicine to refer to the non-protein, pigment part of hemoglobin and related molecules. * The iron atom at the center of the heme group binds directly to oxygen. * A deficiency in heme synthesis can lead to certain types of anemia. * The characteristic red color of blood is due to the heme in hemoglobin.
Advanced Usage
- Heme iron: Refers to the form of iron found in heme, which is derived from animal sources like meat and is more easily absorbed by the body than non-heme iron from plants.
- Nutritionists note that heme iron from red meat has high bioavailability.
- In broader scientific contexts, "heme" can refer to the functional group itself, which is a component of various hemoproteins (heme-containing proteins) like cytochromes, which are involved in electron transport.
Variants and Related Words
- Haem: The British English spelling variant of "heme."
- Heme group: A more specific term emphasizing its role as a prosthetic group within a larger protein.
- Hemoprotein (noun): A protein that contains a heme group, such as hemoglobin, myoglobin, or cytochrome.
- Porphyrin (noun): The larger class of organic compounds to which the heme structure belongs. Heme is an iron-containing porphyrin.
Synonyms
- Iron protoporphyrin: A more precise chemical name for the most common type of heme (heme B).
- Haem (variant spelling).
Related Phrases and Concepts
- Heme biosynthesis: The multi-step biochemical pathway by which heme is produced in the body.
- Disorders of heme biosynthesis are called porphyrias.
- Heme pocket: The specific region within a protein (like hemoglobin) where the heme group is embedded and protected.
- Oxygen-binding site: A functional description of the heme group's primary role.
Noun
- a complex red organic pigment containing iron and other atoms to which oxygen binds