2-Amino-2-hydroxymethyl-propane-1,3-diol, also known as tris(hydroxymethyl)aminomethane (Tris) is probably the most common biochemical buffer, being stable, unreactive and compatible with most proteins and other biomolecules. As such, it is also used very frequently in studies involving metal ions. It is known to coordinate Cu(II). Although often ignored, this feature affects interactions of Cu(II) ions with biomolecules, as Tris is usually used in a high molar excess. Therefore, it is important to have precise knowledge on the stoichiometry, stability and reactivity of cupric Tris complexes. The literature data are incoherent in this respect. We reinvestigated the complex formation in the Tris-Cu(II) system by potentiometry, UV-vis and EPR at a broad range of concentrations and ratios. We found, contrary to several previous papers, that CuTris2 is the maximum stoichiometry, and, at neutral pH dimeric species are formed. Consequences of these results for studies of biomolecules, including Alzheimer's A� peptide, are discussed.

Cu(II) complexes of Tris: Comprehensive view and consequences for toxicological research

244th National Meeting (2012)

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