Pipecolic Acid

Pipecolic acid (PA) is the major metabolic intermediate of lysine in the mammalian brain. Lysine degradation may occur in mitochondria by a bifunctional enzyme complex α-aminoadipic semialdehyde synthase through its lysine-ketoglutarate reductase and saccharopine dehydrogenase activities. The transamination of amino group in α-ketoglutarate leads to the intermediate saccharopine which is converted to acetyl-CoA and enters the citric acid cycle. Lysine can also be degraded by an alternative pathway in the peroxisomes releasing PA which is subsequently oxidized to α-aminoadipic semialdehyde, joining the saccharopine pathway. Some actions in the central nervous system have been attributed to PA because it is considered a modulator that increases the release and decreases the uptake of γ-aminobutyric acid (GABA) by brain neurons.