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7

Bioinorganic Chemistry: A Short Course, Second Edition, by Rosette M. Roat-Malone
Copyright © 2007 John Wiley & Sons, Inc.

IRON - CONTAINING PROTEINS

AND ENZYMES

7.1 INTRODUCTION: IRON - CONTAINING PROTEINS WITH

PORPHYRIN LIGAND SYSTEMS

Iron is the most abundant transition metal found in biological systems with a
percentage by weight in the human body — for instance, 5.0 × 10 − 3 %. Therefore,
it is not surprising that iron - containing proteins and enzymes are found in huge
numbers and varieties in all biological species. First, one might classify iron -
containing species in two categories: those containing a porphyrin ligand
system — an iron - bearing heme moiety — and those not containing porphyrin
ligands — non - heme iron - containing proteins. This chapter will describe some
proteins and enzymes with porphyrin ligand systems with non - heme systems
being described briefl y in Section 7.9. A section devoted to myoglobin and
hemoglobin (7.2) will be followed by six sections (7.3 – 7.8) discussing the ubiq-
uitous cytochrome metalloenzymes.

7.2 Myoglobin and Hemoglobin,

This section outlines the chapter devoted to iron - containing oxygen carriers
and their synthetic models in the fi rst edition of this text.^1 Reversible coordina-
tion of dioxygen (O 2 ), along with its transport through the bloodstream of
vertebrates (and many invertebrates) by the iron - containing metalloproteins