Allosteric effects in norbadione A. A clue for the accumulation process of 137Cs in mushrooms

A fruitful combination of potentiometry, absorption spectrophotometry, ESMS and 1H NMR enabled the characterisation of two caesium complexes with norbadione A and the determination of the respective stability constants of a mononuclear and a dinuclear caesium complex at pH ∼ 6; a preliminary study allowed the assignment of five protonation sites of this pigment; a positively cooperative binding of the second Cs+ cation was observed.