Taenia crassiceps metacestodes have cytochrome oxidase aa(3) but not cytochrome o functioning as terminal oxidase

In mitochondria obtained from Taenia crassiceps metacestodes; carbon monoxi de difference spectra reveal signals characteristic of the classical mitoch ondrial oxidase, cytochrome era,, as well as signals suggesting the presenc e of 'cytochrome o'. In the present work, using photodissociation spectroph otometry and analysis of the haem groups, we conclude that then is no harm O in these larvae, and that the only cytochrome that functions as terminal oxidase is cytochrome c oxidase, aa(3). At temperatures between - 70 and - 100 degreesC, the energy of activation for CO reassociation with cytochrome a(3) was 10.5 kcal mol(-1), and for oxygen binding 7.8 kcal mol(-1). (C) 2 001 Elsevier Science B.Y. All rights reserved.