1D-myo-inositol hexakisphosphate + phosphate + H(+) => 6-diphospho-1D-myo-inositol pentakisphosphate + H2O
1d-myo-inositol hexakisphosphate + phosphate + h(+) => 6-diphospho-1d-myo-inositol pentakisphosphate + h2o