# What type of compound is hemoglobin?

Jan 23, 2017

A porphyrin-containing metalloprotein.

#### Explanation:

At a simple level, we can say that hemoglobin (a.k.a. haemoglobin) is a metalloprotein. Its molecular mass is about $64000$, which gives you some idea as to the complexity of the molecule.

One molecule of hemoglobin contains $4$ heme groups, each of which contains a single atom of iron. The iron atom is directly bound to $5$ surrounding nitrogen atons in a porphyrin ring. Note that it is not directly bound to a carbon atom, so heme and hemoglobin are not counted as organometallic.

Apart from these $4$ iron atoms, the rest of the hemoglobin molecule is organic, containing several protein chains.

It is interesting to compare hemoglobin with chlorophyll, a somewhat simpler metalloprotein that has magnesium instead of iron.