Cytochrome a3: destruction by light.

Spectroscopic measurements on cultures of Prototheca zopfii irradiated with blue light revealed that inhibition of respiration was accompanied by destruction of cytochrome a(3). One of the three b-type cytochromes and one of the two c-type cytochromes of this organism were also affected. Cytochrome oxidase of yeast (not resolved into the a and a(3) components) and cytochrome a(3) of beef-heart mitochondria were also destroyed by blue light.