Investigation of the ternary D-myo-inositol 1,2,6-tris(phosphate)-spermine-Zn2+ system in solution

Interactions of Ins(1,2,6)P-3 (IP), with spermine (Spm) and zinc cations ha ve been studied by potentiometric and P-31 NMR titrations. In the 4-11 pH r ange, two IPSpmZn(2)H(3) and IPSpmZn(2)H mixed complexes are formed which a re largely predominant with respect to the binary species. According to 31P NMR titration it is likely that one of the zinc cations preferably binds p hosphates P1 and P6. The adduct formation between Ins(1,2,6)P-3 and spermin e seems also favourable to the formation of the mixed complexes. The occurr ence of ternary complexes involving inositol-phosphates, biogenic amines, a nd metallic cations may be of relevance in the regulation of biological pro cesses. (C) 2001 Elsevier Science B.V. All rights reserved.