A flavoprotein has been extracted from the mitochondria ofArum spadix. The prosthetic group is flavine-adenine-dinucleotide and the enzyme behaves as a DPN-specific cytochrome c reductase. It is also autoxidizable. Its respiratory function is discussed.
The existence of an autoxidizable flavoprotein in extracts from Arum spadices was observed by James and Beevers (1950) and its possible respiratory significance recognized. Extraction from the tissue in a form suitable for further investigation was not found possible; but its extraction and partial purification from separated mitochondria has now been achieved. In the following paper the method of extraction and the examination of the product are described. The enzyme proves to be a fairly stable flavoprotein with a flavine-adenine-dinucleotide (FAD) prosthetic group, a high degree of specificity for DPN (coenzyme I) and the ability to reduce cytochrome c rapidly. It is also autoxidizable and the reductase and terminal oxidase functions have not yet been separated.