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Abstract
Post-mitochondrial supernatants isolated from Tetrahymena pyriformis contained high specific activities of antimycin A-insensitive NADH- and NADPH- cytochrome c oxidoreductases, acid and alkaline p-nitrophenylphosphatases, DNase and ATPase; many of the enzymes associated with mammalian microsomes were not present at detectable levels. The only haem detected was protohaem; cytochromes b 5, P 450 and P 422 were present in microsomal fractions, and ethyl morphine and aniline HC1 produced distinct changes in difference spectra. Post-mitochondrial supernatants were subfractionated by density gradient centrifugation. The distributions of NADH- and NADPH-cytochrome c oxidoreductases were different, and several distinct particles containing the latter enzyme system were distinguished. The distributions of acid p-nitrophenylphosphatase, acid DNase and ATPase were all different and indicative of several functionally distinct membrane systems. Alkaline p-nitrophenylphosphatase was non-sedimentable.
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