D-sedoheptulose 7-phosphate isomerase (, sedoheptulose-7-phosphate isomerase, phosphoheptose isomerase, gmhA (gene), lpcA (gene)) is an enzyme with systematic name D-glycero-D-manno-heptose 7-phosphate aldose-ketose-isomerase. This enzyme catalyses the following chemical reaction
In Gram-negative bacteria the enzyme is involved in biosynthesis of ADP-L-glycero-ò-D-manno-heptose.