An Electrochemical Study of Hemoglobin

In the course of a series of investigations on the physical chemistry of hemoglobin now being carried on in the Laboratory of Physical Chemistry of the Harvard Medical School, Dr. E. J. Cohn and Dr. R. M. Ferry discovered certain abnormalities in the behavior of a hydrogen electrode immersed in solutions of hemoglobin and oxyhemoglobin. On studying the matter further they found that any inert electrode when dipped into a hemoglobin solution gave a fairly de&rite potential which varied with the degree of oxygenation of the hemoglobin, It was at first thought that this potential might be the oxidation-reduction potential of the system hemoglobin-oxyhemoglobin, and in order to investigate this possibility the present work was undertaken by the author. It was soon found that the titration method of determining oxidation potentials, now being applied in this laboratory to a study of quinones (1, 2) and first proposed by Clark (3), was applicable to hemoglobin solutions; the system of oxidized and reduced compounds involved, however, was not oxyhemoglobin-hemoglobin, but hemoglobin-methemoglobin. The reactions which are the basis of the method are: hemoglobin + K3Fe(CN)6 + methemoglobin; and 2 methemoglobin + NazSz04 + 2 hemoglobin.