Definition

1. Noun:
   • A complex red organic pigment containing iron and other atoms to which oxygen binds: Haem is the iron-containing component of haemoglobin, the protein in red blood cells that carries oxygen.

Usage

• The word "haem" is a scientific term used primarily in biochemistry, physiology, and medicine. It refers to the specific non-protein, pigment part of larger molecules like haemoglobin and myoglobin.

Examples

• Noun:
  • Oxygen binds reversibly to the iron atom within the haem group.
  • The characteristic red colour of blood is due to the presence of haem.

Advanced Usage

• "Haem biosynthesis": Refers to the multi-step biochemical pathway by which haem is produced in the body.
  • Defects in haem biosynthesis can lead to diseases like porphyria.
• "Haem iron": A specific form of dietary iron found in animal products, bound within the haem molecule.
  • Haem iron is more readily absorbed by the body than non-haem iron from plants.

Variants and Related Words

• Heme (noun): The American English spelling of "haem".
  • The heme group is a porphyrin ring with a central iron ion.
• Haemoglobin (noun): The oxygen-transporting protein in red blood cells, which contains four haem groups.
  • Haemoglobin levels are a common blood test.
• Haematology (noun): The branch of medicine concerned with the study of blood, blood-forming organs, and blood diseases.
  • She is a specialist in haematology.

Synonyms

• Heme: The direct synonym, differing only in regional spelling (AE vs. BE).
• Iron protoporphyrin: A more technical chemical name for the haem molecule.
• Ferroheme: A term specifying the reduced (ferrous, Fe²⁺) form of haem that binds oxygen.

Related Phrases and Compounds

• Haem group: The standard term for the haem unit as part of a larger protein.
  • The enzyme cytochrome c contains a haem group essential for its function.
• Haem oxygenase: An enzyme that breaks down haem.
  • Haem oxygenase activity produces biliverdin, carbon monoxide, and free iron.

Noun

1. a complex red organic pigment containing iron and other atoms to which oxygen binds