The anomeric configuration of the D-mannosyl retinyl phosphate formed in rat liver microsomes.

Alkaline hydrolysis at 65 degrees converted D-mannosyl retinyl phosphate primarily into D-mannose 2-phosphate which was identified by its behavior on paper chromatography in two solvent systems, as well as by its resistance to acid hydrolysis under conditions that converted authentic alpha-D-mannosyl phosphate to mannose. When the D-mannosyl retinyl phosphate was hydrolyzed in alkali at 100 degrees, the main product was beta-D-mannosyl phosphate and not the alpha anomer (as shown by chromatography with authentic samples on thin layers of silica gel). No evidence for enzymatic hydrolysis of D-mannosyl retinyl phosphate by alpha-mannosidase was obtainable. It is concluded that the compound under investigation is beta-D-mannosyl retinyl phosphate.