Confirmation of the identity of the major phospholipid in human lens membranes.

Abstract

PURPOSE: To confirm the identity of the major component of the human lens membranes proposed in 1994 to be dihydrosphingomyelin (DH-SPH). METHODS: DH-SPH was prepared by catalytic hydrogenation of the double bond between carbons 4 and 5 of sphingomyelin (SPH). DH-SPH was characterized by phosphorus-31 (31P) and proton (1H) nuclear magnetic resonance (NMR) spectroscopy at different reaction times. The spectroscopic data were compared to those of the major component extracted from human lens membranes. RESULTS: Both the 1H NMR and the 31P NMR spectral resonances of the prepared DH-SPH matched those for the once "unknown phospholipid" that constitutes approximately half the human lens phospholipids. CONCLUSIONS: The match of the spectroscopic NMR data obtained for the DH-SPH prepared by hydrogenation of SPH and those for the major phospholipid isolated from the human lens membranes confirms the identity of this sphingolipid as D-erythro-4,5-dihydrosphingomyelin.