The substrate fructose-6-phosphate(F6P),the products fructose-1,6-bisphosphate(FBP) and phosphate(Pi) protected PFP against the DEPC modification,suggesting that the modified histidine residue resides at active sites.

• 底物F6P、产物果糖1；6-二磷酸(FBP)、P i及激活剂果糖2；6-二磷酸(F2；6BP)均可保护酶免被DEPC失活；底物PP i却没有保护作用.