protohemin vs hemin

protohemin and hemin both are nouns.

Word	Noun	Adjective	Verb	Adverb
protohemin	Yes	No	No	No
hemin	Yes	No	No	No

As nouns, protohemin and hemin are synonyms defined as:

protohemin and hemin: a reddish-brown chloride of heme; produced from hemoglobin in laboratory tests for the presence of blood

protohemin (noun)	hemin (noun)
a reddish-brown chloride of heme; produced from hemoglobin in laboratory tests for the presence of blood	a reddish-brown chloride of heme; produced from hemoglobin in laboratory tests for the presence of blood