Decrease of Haem a Content in the Heart Muscle of Copper‐deficient Swine

SUMMARY Two samples of heart muscle from copper‐deficient pigs and a control sample from a normal pig were analysed for haem a and protohaem content firstly by spectrophotometric determination of the mixture of the two haemochromes and secondly by separation of the two free porphyrins by fractional extraction from ether by hydrochloric acid. The haem a content was found greatly decreased in copper‐deficiency. The low haem a content could be due either to a rôle of copper in haem a synthesis (as distinct from the synthesis of the whole enzyme) or to a rôle of copper in the biosynthesis of the holoenzyme at an early stage. It appears possible to ascribe the loss of activity of cytochrome oxidase in copper‐deficiency entirely to this factor and this loss therefore cannot prove that copper is necessary for cytochrome oxidase activity, although it does not exclude this possibility.