Photosensitivity of Hæm Compounds

Abstract

Haldane and Lorrain Smith¹ discovered that carboxyhæmoglobin is sensitive to light, and several workers have shown that this property is shared by other ferrohæm–carbon monoxide compounds. Until Keilin and Hartree² found that the cyanide compounds of ferroperoxidase and myoglobin were light-sensitive, it was generally believed that carbon monoxide compounds were unique in this respect. We have now found that oxyhæmoglobin, nitric oxide hæmoglobin and ethyl isocyanide hæmoglobin are light-sensitive, thus showing that all the known ligands able to combine with ferrohæmoglobin are qualitatively similar.