Determination of molecular mass of the aroid alternative oxidase by radiation-inactivation analysis.
The functional molecular mass of the cyanide-resistant salicylhydroxamate-sensitive duroquinol oxidase activity from Sympocarpus foetidus (skunk cabbage) and Sauromatum guttatum spadix mitochondria was determined by radiation-inactivation analysis. The functional molecular mass for the oxidase activity was found to be 26,700 Da for skunk cabbage and 29,700 Da for Sauromatum guttatum mitochondria frozen at -70 degrees C. Irradiation of dried mitochondrial samples resulted in a larger target size of 38,000 Da, and in some cases, a stimulation of activity at low dose of radiation. The functional molecular mass of cytochrome c oxidase activity from skunk-cabbage and bovine heart mitochondria was also investigated. Dried and frozen mitochondrial samples from both species yielded similar target sizes, in the range 70,900-73,400 Da. Purified bovine heart cytochrome c oxidase was also irradiated, and yielded a functional molecular mass of 66,400 Da. The target size of cytochrome c oxidase agrees with literature values insofar as the target size is considerably smaller than the molecular mass of the entire complex.
Berthold
D A
DA
Department of Botany, Duke University, Durham, NC 27706.
Fluke
D J
DJ
Siedow
J N
JN
D001937:Brassica / Q000201:enzymology*; D003576:Electron Transport Complex IV / Q000528:radiation effects; D005954:Glucosephosphate Dehydrogenase / Q000528:radiation effects; D008970:Molecular Weight; D010088:Oxidoreductases / Q000528:radiation effects; D010944:Plants
D010088:Oxidoreductases; C020094:duroquinol oxidase; D005954:Glucosephosphate Dehydrogenase; D003576:Electron Transport Complex IV