A comparative study of the succinic dehydrogenase-cytochrome system in heart muscle and in kidney

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Abstract
Methods of obtaining enzyme prepns. from heart muscle and kidney suitable for the study of the succinic oxidase system and for the spectroscopic study of the cytochromes were descr. The factors involved in the measurement of the succinic dehydro-genase activity and of the complete succinic oxidase system were investigated. Kidney possessed essentially the same cyto-chrome system as was found in heart muscle. There was no evidence that cytochrome b1 replaced cytochromes b and c in the kidney. Quantitative measurements of the amts. of hematin compounds in the enzyme prepns. suggested that both contained unknown hematin compounds, whose spectra were not normally visible. Evidence was produced suggesting that cytochrome b was involved in the catalysis of the reduction of methylene blue by succinate. The enzyme prepns. were colloidal solns. of particles, which were probably derived from some subcellular structure in the tissue. The fact that the molar concn. of Cu in the heart-muscle prepn. was of the same order of magnitude as that of the hematin compounds suggested that a Cu-protein compound might have some catalytic function in the prepn. The Q02 (at 37[degree]) of the cytochrome c in the heart-muscle prepn. was 38,000, i.e., about half the value in yeast.