THE ENZYMATIC SYNTHESIS OF OXALACETATE FROM PHOSPHORYL-ENOLPYRUVATE AND CARBON DIOXIDE

Abstract

The present work is concerned with an enzyme, obtained from an acetone powder of spinach leaves, which catalyzes the carboxylation of phosphorylenolpyruvate’ to yield, under the conditions of isolation here employed, oxalacetate and inorganic phosphate. Pyruvate or pyruvate plus ATP will not substitute for PEP. Reduced triphosphopyridine nucleotide is not added to the reaction mixture and malate does not accumulate. The reaction thus appears to be distinct from the reductive carboxylation of pyruvate to malate by the “malic” enzyme (I). The present reaction may represent a mechanism for the Wood and Werkman reaction in which pyruvate is carboxylated to OA (2). This reaction, as has been shown by Utter and Wood (3), is activated by the addition of ATP. Enzymes catalyzing the Wood and Werkman reaction have now been shown to be present in bacteria (2, 4), pigeon liver (5, 6), and higher plants (7). In two recent communications (8, 9), Utter and Kurahashi describe the reversible formation of OA and ATP from PEP, ADP, and HC03 in the presence of an enzyme from pigeon liver. It seems probable that the reaction described by Utter and Kurahashi is the same as that described in the present work, with the addition of a second enzyme catalyzing the transfer of phosphorus from a labile intermediate to ADP. A preliminary report of the present work has appeared (10). Several recent reviews of carboxylation reactions leading to the formation of a dicarboxylic acid are now available (11-13).