Cytochrome and respiratory enzymes

Abstract The object of this paper is the study of the functional relationship between the intracellular hæmatin compounds and the oxidising enzymes such as dehydrases and oxidases. It was shown previously (1925-1927) that aerobic organisms contain a very widely distributed intracellular hæmatin pigment-cytochrome-which can undergo reversible oxidation and reduction without being destroyed. Being the only compound directly visible in the living cell, cytochrome gives us important indications, not only of its own activity but also of that of other components of the respiratory system of the cell. The present paper will first deal with the thermostable peroxidase of yeast and other cells, and with the true thermostable oxidases such as the indophenol oxidase of yeast and muscle cells and the polyphenol oxidase of potato. This will be followed by the study of intracellular hæmatin compounds, and especially of the effects of various factors on the oxidation and reduction of cytochrome. The results of this study will enable us to determine the nature of the relationship between the oxidising enzymes and the intracellular hæmatin compounds, and this will help to elucidate at least one portion of the complicated respiratory mechanism, of the cell.