Biosynthesis of 4D-hydroxysphinganine by the rat. En bloc incorporation of the sphinganine carbon backbone.

Rats were injected intravenously with erythro-DL-[1-3H]sphinganine. Radiolabeled 4D-hydroxysphinganine (phytosphingosine) was detected (in addition to sphinganine and 4-sphingenine) in glycolipid- and sphingomyelin-rich fractions from intestine and kidney. Identification of these bases was achieved following hydrolysis of the these fractions and conversion of the long chain bases to their N-dinitrophenyl (Dnp) derivatives. Dnp-4D-hydroxy[3H]sphinganine was characterized by: comigration on thin-layer chromatography with authentic standard and detection of pentadecanol and Dnp-[3H]serinol. These results strongly suggest that in mammalian tissues the C18 carbon backbone of 4D-hydroxysphinganine can be derived (en bloc) from sphinganine.