Results: Saccharopine dehydrogenase, entry of lysine into the mitochondrial degradation pathway, was present in liver and kidney mitochondria but not detectable in brain. Aminoadipate semialdehyde dehydrogenase and aminoadipate transaminase activity were found in cytosolic and mitochondrial fractions of all tested tissue. Pipecolate oxidase, representing the peroxisomal pathway, was detected in kidney and brain. Strikingly, clofibrate treatment decreased instead of increasing glutaric acid levels.