Binding citrate/DNA in presence of divalent cations. Potential mimicry of acidic peptides/DNA interactions.

Citric acid whose structure is comparable to that of small acidic peptides, can bind to DNA in the presence of divalent cations (Cu2+, Fe2+, Zn2+, Mg2+). Citrate-DNA interaction occurs also in a cell homogenate and in this experimental model too requires the presence of natural divalent cations. In fact the addition of 2 mM EDTA to cell homogenate strongly decreases the DNA-citrate binding. The results demonstrate that divalent cations can act as bridges between two acidic molecules and that citric acid can mimic the structure of acidic peptides.