A Number of Properties of Proto-Mitochondria from Rat Liver

A number of properties of isolated proto-mitochondria (small young animal cell organelles) were studied. Proto-mitochondria were obtained by filtration of the light fraction of rat-liver mitochondria through calibrated millipore filters with a pore diameter of 0.45 μm. It was found that proto-mitochondria have a decreased ability to synthesize ATP due to their much lower content of ATP synthetase. The level of cytochromes in proto-mitochondria and mitochondria differ little. It was found that proto-mitochondria have more flavoproteins than mitochondria. It was demonstrated that proto-mitochondria (unlike mitochondria) contain almost none of the lipofuscin “aging pigment.” These differences reflect the processes of intracellular maturation of proto-mitochondria to mitochondria and subsequent aging to post-mitochondria. The results are important for understanding the role of proto-mitochondria in the cellular metabolism of specialized animal cells.