title: Mechanism of enzymic isomerization and epimerization of D-erythrose 4-phosphate.
abstract: The mechanism of the enzymic isomerization and epimerization of D-erythrose 4-phosphate (Ery4P) by an enzyme preparation from bovine liver was investigated with the use of 2H2O. The incorporation of 2H was quantitatively determined by a procedure using gas chromatography-mass spectrometry. About one atom of 2H was incorporated per molecule of the enzymic epimerization reaction product of Ery4P (D-threose 4-phosphate) or that of D-ribulose 5-phosphate. Computer simulation of the Ery4P isomerization reaction indicated that the 2H of 2H2O was not directly incorporated into the enzymic reaction product (D-erythrulose 4-phosphate). Instead, intramolecular transfer of hydrogen atoms had occurred.
mesh_terms: D002238:Carbohydrate Epimerases / Q000378:metabolism*; D003903:Deuterium; D008401:Gas Chromatography-Mass Spectrometry; D007536:Isomerism; D007700:Kinetics; D008956:Models, Chemical; D013403:Sugar Phosphates / Q000378:metabolism*
chemical_list: D013403:Sugar Phosphates; C026959:erythrose 4-phosphate; D003903:Deuterium; D002238:Carbohydrate Epimerases; C022553:ribulosephosphate 3-epimerase