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Related to protoporphyrin: Zinc Protoporphyrin
A metal-free porphyrin, C34H34N4O4, that combines with ferrous iron to form the heme group in hemoglobin and myoglobin, and with ferric iron to form the hemin group in catalase and some cytochromes.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Biochemistry) 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 and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014