The Microsomal Fraction from Tetrahymena pyriformis Strain ST: Characterization and Subfractionation

Abstract

SUMMARY Post-mitochondria1 supernatants isolated from Tetrahymena pyriformis con- tained 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; cyto- chromes b5, P,,, and P,,, were present in microsomal fractions, and ethyl morphine and aniline HCl produced distinct changes in difference spectra. Post-mitochondria1 supernatants were subfractionated by density gradient centrifugation. The distri- butions 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. Al- kaline p-nitrop henylphosphatase was n on-sedimen table.