... of PNPmonomers), determined by absorption measurements. Con-centrations of the ligand varied in the range 0.05–6.4 lm.Concentrations of protein and ligand refer to the situationprior to mixing ... (Docs S1 and S2; Figs S1 and S2).Confirmation of picomolar binding constant by titration experiments To confirm strong binding of DFPP-DG by calf spleenPNP, the dissociation constant for this complex ... However, in contrast to immucillins, which show apKafor pentose protonation at neutral pH (pK = 6.9)[5], multisubstrate analogue inhibitors are anions, oreven a mixture of mono- and di-anions at...