Fig. 4. Specific activities of DIPPs with 1-PP-Ins(4,5)P2 (1), known substrates 1-PP-InsP5 and 5-PP-InsP5 and controls. Experiments were conducted in buffer containing Mg2+ (A) or Mn2+ (B). Data shown represent the formed concentration of Pi (micromolar) per enzyme concentration (micromolar) per minute. A630 was converted to Pi concentration (micromolar) using the equation A630 = 0.01897[Pi] – 0.5877 (Mg2+ containing buffer) or A630 = 0.01923[Pi] + 0.1053 (Mn2+ containing buffer). C. Structures of compounds examined, including methylenebisphosphonate (PCP) analogues of InsP7, and diadenosine polyphosphates Ap3A and Ap5A.
