Migration during hydrolysis of esters of glycerophosphoric acid; the chemical hydrolysis of L-alpha-glycerylphosphoryl-choline.

In view of the biological significance of the lecithins a.nd of the fact that t;hey have been known to the chemist for a hundred years (l), it is rather surprising that there should still remain doubts concerning the position of the phosphoric acid. Until recently it has been assumed by most workers that lecithins could be hydrolyzed chemically without causing a change in the position of the phosphoric acid and that the constitution and configuration of the resulting glycerophosphoric acid would be identical with that of the original phosphatide. Thus the presence of aand pglycerophosphoric a.cids (a-CPA and /3-GPA) in the hydrolysis products of natural lecithins was interpreted as indicating t,he occurrence of both the a! and /3 forms (24), and attempts were made to obtain these isomers in pure state (4-7). More recent evidence @--lo), however, although not fully conclusive, seems to be strongly in favor of the occurrence of a reversible phosphoric acid migration during the chemical hydrolysis of lecithins. It was thought that an investigation of the acid and alkaline hydrolysis of L-or-glycerylphosphorylcholine (L-(w-GPC), obtainable from autolyzed beef pancreas (11) and by synthesis (12), would provide information which might be useful in the elucidation of the reaction mechanism underlying the chemical hydrolysis of lecithins. The use of this pure enantiomer as substrate makes it possible -to follow the course of the hydrolysis and especially the migration of the phosphoric acid group by physical (optical) as well a,s chemical means.