Isolation of Peroxisomes from Mouse Brain Using a Continuous Nycodenz Gradient: A Comparison to the Isolation of Liver and Kidney Peroxisomes.

In the central nervous system (CNS) peroxisomes are present in all cell types, namely neurons, oligodendrocytes, astrocytes, microglia, and endothelial cells. Brain peroxisomes are smaller in size compared to peroxisomes from other tissues and are therefore referred to as microperoxisomes. We have established a purification procedure to isolate highly purified peroxisomes from the central nervous system that are well separated from the endoplasmic reticulum and mitochondria and are free of myelin contamination. The major difficulty in purification of brain peroxisomes compared to peroxisomes from liver or kidney is the presence of large amounts of myelin in the CNS, which results in contamination of the subcellular fractions. Hence, the crucial step of the isolation procedure is the elimination of myelin by the use of a sucrose gradient, since without the elimination of myelin no significant enrichment of purified peroxisomes can be achieved. Another difficulty is that in brain tissue the abundance of peroxisomes decreases significantly during postnatal development. We provide a detailed protocol for the isolation of peroxisomes from mouse central nervous system as well as a protocol for the isolation of peroxisomes from the liver and kidney using a continuous Nycodenz gradient.