PURIFICATION AND CHARACTERIZATION OF MEMBRANE-BOUND CO-REACTIVE HEMOPROTEIN FROM TETRAHYMENA-PYRIFORMIS MITOCHONDRIA

A CO-reactive hemoprotein was purified from the mitochondrial membrane fraction of Tetrahymena pyriformis. It showed absorption peaks at 615 and 455 nm in the reduced form and an alpha peak at 565 nm in the pyr idine ferrohemochrome spectrum. Although the spectral properties were apparently similar to those of 'cytochrome a620' which was previously proposed as a mitochondrial terminal oxidase in T. pyriformis, it did not contain any molecules of heme a or copper atoms. Further, it showe d neither cytochrome c oxidase nor cytochrome c peroxidase activity. T hese results suggest that 'cytochrome a620' may not be the terminal ox idase in the mitochondrial respiratory chain of T pyriformis.