<p>This entry describes the sucrose phosphate phosphohydrolase from plants and cyanobacteria (SPP). However, a closely related group of sequences from bacteria and archaea may prove to catalyze the same reaction. SPP is a member of the Class IIB subfamily of the Haloacid Dehalogenase (HAD) superfamily of aspartate-nucleophile hydrolases. SPP catalyzes the final step in the biosynthesis of sucrose, a critically important molecule for plants. </p><p>Sucrose phosphate synthase (SPS), the prior step in the biosynthesis of sucrose contains a domain, which exhibits considerable similarity to SPP albeit without conservation of the catalytic residues. The catalytic machinery of the synthase residesin another domain. It seems likely that the phosphatase-like domain is involved in substrate binding, possibly binding both substrates in a "product-like" orientation prior to ligation by the synthase catalytic domain.</p> Sucrose phosphatase, plant/cyanobacteria