Membrane-Bound Mitochondrial DNA: Isolation, Transcription and Protein Composition

Abstract
Mitochondrial membrane-bound DNA complex from bovine heart mitochondria lysed in the presence of Triton X-100 was isolated by differential centrifugation. The yield of “nucleoid” is about 30 μg protein/mg mitochondrial protein. It contains about 3-5 μg DNA/mg protein and varying amounts of RNA. The heart mitochondrial nucleoid actively synthesizes RNA. The nucleoid fraction contains about sixteen different proteins as evidenced by urea-SDS gel electrophoresis and about twenty-one proteins as evidenced by acid-urea gel electrophoresis. ft appears that the nucleoid is attached to the inner membrane since it does contain cytochromes.