Saccharopine is an intermediate in the metabolism of amino acid lysine. It is a precursor of lysine in the alpha-aminoadipate pathway which occurs in fungi and euglenids. In mammals and seed plants saccharopine is an intermediate in the degradation of lysine, formed by condensation of lysine and alpha-ketoglutarate.
The reactions involved, catalysed by saccharopine dehydrogenases, are:
Saccharopinuria (high amounts of saccharopine in the urine) and saccharopinemia (an excess of saccharopine in the blood) are conditions present in some inherited disorders of lysine degradation.
Saccharopine was first isolated in 1961 from baker's yeast (Saccharomyces cerevisiae, hence the name) by Darling and Larsen.