Transaldolase important for the balance of metabolites in the pentose-phosphate pathway. Involved in xylose fermentation to ethanol. D-glyceraldehyde 3-phosphate + D-sedoheptulose 7-phosphate = beta-D-fructose 6-phosphate + D-erythrose 4-phosphate kcat is 4114 min(-1) with D-erythrose 4-phosphate as substrate and 4151 min(-1) with D-fructose 6-phosphate as substrate. Optimum pH is 7.5. Optimum temperature is 40-45 degrees Celsius. Carbohydrate degradation; pentose phosphate pathway; D-glyceraldehyde 3-phosphate and beta-D-fructose 6-phosphate from D-ribose 5-phosphate and D-xylulose 5-phosphate (non-oxidative stage): step 2/3. Monomer. Belongs to the transaldolase family. Type 1 subfamily.