Comparative electrophoretic studies of polypeptides in leaf, petiole and root mitochondria from spinach

Publisher Website
Google Scholar
Abstract
Essentially chlorophyll‐free preparations of mitochondria from different tissues of the same plant can be obtained by a combined three step preparation procedure involving differential centrifugation, partition in aqueous polymeric two‐phase system and centrifugation in a Percoll gradient. The polypeptide patterns of mitochondria from photosynthetic (leaves) and non‐photosynthetic (petioles and roots) tissue from spinach were compared by use of SDS‐electrophoresis.About 35 polypeptides were found in leaf mitochondria with molecular weights from 14 to 103 kdalton. The polypeptide patterns of the membrane fractions and matrix fractions showed great differences. The membrane fractions contained significantly more polypeptide bands than the matrix fractions. The polypeptide patterns of mitochondria from photosynthetic and non‐photosynthetic tissues showed some striking differences. The 15.9, 41.7, 50.7 and 101 kdalton polypeptides were clearly detected in leaf mitochondria but these polypeptides were not found or found in only small amounts in petiole and root mitochondria. The differences were mainly associated with the matrix fractions. Staining with 3,3′,5,5′‐tetramethylbenzidine and hydrogen peroxide for heme containing polypeptides showed that the polypeptides which differ do not contain heme.