Hematinoglobulin

Part of speech: noun

Definitions

1. A globulin-type protein that has hematin, an iron-containing pigment derived from heme, attached to it
2. A blood-related protein complex in which a globulin is combined with hematin, the oxidized form of heme
3. An iron-bearing protein compound formed when hematin, a heme derivative, binds to a globulin molecule

Etymology: The word is an older spelling of "hemoglobin," the protein in red blood cells that carries oxygen. Its first half, "hematin," combines the Ancient Greek "haima" ("blood") with the chemical suffix "-in," which chemists attached to substances they had isolated. "Hematin" was the name given to the iron-containing compound derived from blood pigment, so the "-o-" links it to the second half, "globulin." That term comes from Latin "globus" ("ball, sphere") plus "-in," and in protein chemistry it names a family of proteins that are soluble in water but not in pure alcohol. Read literally, the coinage is a blend of two chemical names, one describing the blood pigment and one describing a protein class. The spelling "hemoglobin" later replaced the original form, shortening "haima" to "hem-" and dropping the earlier "-in" ending in favour of the modern "-in" compound.