Concerning the catalytic hydrogenation of polyprenyl phosphate-mannose synthesized by the retina

Catalytic hydrogenolysis has been used as a means of distinguishing between classes of polyprenyl phosphate sugars which contain saturated alpha-isoprene units from those in which this grouping is allylic. Catalytic hydrogenation of dolichyl phosphate-[14C]mannose, synthesized by the retina of the embryonic chick was examined using different solvents and catalysts. When performed in chloroform:methanol (2:1), extensive cleavage to water-soluble radioactive material occurred due to hydrolysis caused by the reaction medium, even when buffered with tributylamine. When other solvents were used, considerable adsorption of radio-activity to the catalyst, in addition to variable amounts of hydrolysis, was encountered. Thus, the method is encumbered with artifact and extreme variability depending upon the reaction conditions employed, rendering it less than reliable for the purpose for which it was intended.