The Hydrolysis of Phosphate Esters of a-Hydroxy Acids Catalyzed by Molybdate*

Frequent observations have been made of the increased rate of hydrolysis of relatively labile phosphate compounds in acid molybdate solution (e.g. phosphocreatine (I), acetyl phosphate (2), and 1,3-diphosphoglyceric acid (3)). A study by Weil-Malherbc and Green (4) indicated that ATP, pyrophosphate, phosphoenolpyruvate, and fructosr B-phosphate were hydrolyzed appreciably in the pH range 3 to 5, while fructose 1,6-diphosphate, glucose lphosphate, cY-plycerophosphatc, and glucose B-phosphate were quite stable. The fact that monophosphoglyceric acids form complexes with high optical rotation in the presence of molybdate led to the use of polarimetric procedures for the quantitative determination of these compounds (5). Alolybdate forms complexes with man3 oxygen-containing organic compounds and the affinity for a-hydroxy acids is particularly high (6). The present study began with the observation of Bartlett that the monophosphoglyceric acids are hydrolyzed at widely different< rates in the presence of molybdate (7). The specificity, pH, and temperature dependences have been examined. In the pH range 3 to 5 there is a marked specificity of hydrolysis for phosphate esters of oc-hydroxy acids. A procedure has been worked out for the quantitative