Phosphoketolase

In enzymology, a phosphoketolase (EC 4.1.2.9) is an enzyme that catalyzes the chemical reaction

D-xylulose 5-phosphate + phosphate ⇌ acetyl phosphate + D-glyceraldehyde 3-phosphate + H₂O

Thus, the two substrates of this enzyme are D-xylulose 5-phosphate and phosphate, whereas its 3 products are acetyl phosphate, D-glyceraldehyde 3-phosphate, and H₂O.

This enzyme belongs to the family of lyases, specifically the aldehyde-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is D-xylulose-5-phosphate D-glyceraldehyde-3-phosphate-lyase (adding phosphate; acetyl-phosphate-forming). Other names in common use include D-xylulose-5-phosphate D-glyceraldehyde-3-phosphate-lyase, and (phosphate-acetylating). This enzyme participates in 3 metabolic pathways: pentose phosphate pathway, methane metabolism, and carbon fixation. It employs one cofactor, thiamin diphosphate.