Article ID Journal Published Year Pages File Type
2048872 FEBS Letters 2010 6 Pages PDF
Abstract

The mammalian degradation of lysine is believed to proceed via two distinct routes, the saccharopine and the pipecolic acid routes, that ultimately converge at the level of α-aminoadipic semialdehyde (α-AASA). α-AASA dehydrogenase-deficient fibroblasts were grown in cell culture medium supplemented with either l-[α-15N]lysine or l-[ε-15N]lysine to explore the exact route of lysine degradation. l-[α-15N]lysine was catabolised into [15N]saccharopine, [15N]α-AASA, [15N]Δ1-piperideine-6-carboxylate, and surprisingly in [15N]pipecolic acid, whereas l-[ε-15N]lysine resulted only in the formation of [15N]saccharopine. These results imply that lysine is exclusively degraded in fibroblasts via the saccharopine branch, and pipecolic acid originates from an alternative precursor. We hypothesize that pipecolic acid derives from Δ1-piperideine-6-carboxylate by the action of Δ1-pyrroline-5-carboxylic acid reductase, an enzyme involved in proline metabolism.

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