protoporphyrin IX


A porphyrin derivative that combines with ferrous iron to form the heme of hemoglobin and with ferric or ferrous iron to form the prosthetic groups of substances such as myoglobin, catalase, and the cytochromes.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.