3 hexulose 6 phosphate synthase

3-hexulose-6-phosphate synthase (EC 4.1.2.43, D-arabino-3-hexulose 6-phosphate formaldehyde-lyase, 3-hexulosephosphate synthase, 3-hexulose phosphate synthase, HPS) is an enzyme with systematic name D-arabino-hex-3-ulose-6-phosphate formaldehyde-lyase (D-ribulose-5-phosphate-forming). This enzyme catalyses the following chemical reaction

D-arabino-hex-3-ulose 6-phosphate ⇌ D-ribulose 5-phosphate + formaldehyde

This enzyme requires Mg²⁺ or Mn²⁺ for maximal activity.