Separation of mitochondria from contaminating subcellular structures utilizing silica sol gradient centrifugation

Area of Science:

• Biochemistry
• Cell Biology
• Plant Science

Background:

• Mitochondrial purification is crucial for studying cellular respiration and energy metabolism.
• Existing methods often involve complex steps or result in significant contamination.
• Efficient isolation of intact mitochondria from plant tissues presents unique challenges due to cell wall presence and pigment contamination.

Purpose of the Study:

• To develop and validate a rapid, isosmotic, low-viscosity method for purifying mitochondria from plant tissues.
• To assess the effectiveness of discontinuous Percoll gradients in removing subcellular contaminants.
• To evaluate the physiological integrity and oxidative properties of purified mitochondria.

Main Methods:

• Utilized discontinuous Percoll density gradients for mitochondrial separation.
• Applied the method to etiolated tissues (e.g., potato tuber) and green leaf tissues (e.g., spinach).
• Quantified protein enrichment, chlorophyll contamination, and cytochrome c oxidase activity.

Main Results:

• Achieved significant purification of mitochondria from etiolated and green plant tissues.
• Reduced chlorophyll contamination in spinach mitochondria from ~70 to ~8 µg/mg protein.
• Demonstrated retained respiratory activity and physiological integrity in purified mitochondria.

Conclusions:

• Discontinuous Percoll gradients offer an efficient and rapid method for high-purity mitochondrial isolation from diverse plant sources.
• The method effectively removes common contaminants like chlorophyll, crucial for biochemical analyses.
• Purified mitochondria maintain their integrity and oxidative capacity, suitable for functional studies.