a type of porphyrin that, when combined with an iron atom, forms haem, the oxygen-bearing prosthetic group of the red blood pigment haemoglobin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
A metal-free porphyrin that combines with iron to form the heme of iron-containing proteins.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.