The Magnetic Properties and Structure of Hemoglobin, Oxyhemoglobin and Carbonmonoxyhemoglobin

TLDR

Faraday’s early magnetic studies of blood highlighted large susceptibility differences between oxygenated and deoxygenated blood, while the original hemoglobin nomenclature was established before precise chemical structures were known. The study aims to report magnetic measurements of hemoglobin species and to revise their nomenclature for greater descriptive accuracy. The authors present a new set of names for hemoglobin forms, including accepted synonyms, and outline the criteria for acceptable terminology. Oxyhemoglobin and carbonmonoxyhemoglobin exhibit no unpaired electrons, ferrohemoglobin has four per heme, and the authors identify certain parenthetical expressions as undesirable in the revised nomenclature.

Abstract

Over ninety years ago, on November 8, 1845, Michael Faraday investigated the magnetic properties of dried blood and made a note “Must try recent fluid blood.” If he had determined the magnetic susceptibilities of arterial and venous blood, he would have found them to differ by a large amount (as much as twenty per cent for completely oxygenated and completely deoxygenated blood); this discovery without doubt would have excited much interest and would have influenced appreciably the course of research on blood and hemoglobin.1 Continuing our investigations of the magnetic properties and structure of hemoglobin and related substances,2 we have found oxyhemoglobin and carbonmonoxyhemoglobin to contain no unpaired electrons, and ferrohemoglobin (hemoglobin itself) to contain four unpaired electrons per heme. The description of our experiments and the interpretation and discussion of the results are given below. The current nomenclature of hemoglobin and related substances was formulated at a time when precise information about the chemical composition and structure of the substances was not available. Now that some progress has been made in gathering this information, especially in regard to chemical composition, it is possible to revise the nomenclature in such a way as to make the names of substances more descriptive than the older names, without introducing any radical changes. In formulating the following set of names we have profited by the continued advice of Dr. Alfred E. Mirsky. The names whose use we advocate are given below, followed in some cases by acceptable synonyms. The expressions in parentheses are those whose use we consider to be undesirable.Heme: an iron-porphyrin complex (generic term, used for either ferroheme or ferriheme).Ferroheme (reduced heme): a complex of ferrous iron and a porphyrin.Ferriheme (oxidized heme): a complex of ferric iron and a porphyrin.Ferriheme chloride, …