Purification and properties of yeast transaldolase.

Sedoheptulose-7-phosphate, originally identified as a product of photosynthesis in algae and higher plants (3), has been shown to arise by the action of transketolase on pentose phosphate (4, 5). This reaction occurs in a wide variety of animal (5, 6), plant (5, 7), and microbial cells (8-lo), and evidence has been obtained that the heptulose ester is an intermediate in the formation of hexose monophosphate from pentose phosphate (7, 11, 12, 13). With the isolation of sedoheptulose-7-phosphate from transketolase reaction mixtures (5), it became possible to study directly the conversion of this ester to hexose monophosphate. In an earlier publication from this laboratory (14) it was reported that this reaction requires a source of triose phosphate, and evidence was presented for the accompanying mechanism. The enzyme has been named transaldolase, since it catalyzes the