Multi-metal binding site of serum albumin.

Circular dichroism and electron spin resonance spectroscopy are used to investigate the second specific metal binding site on human, bovine and porcine albumins. Ni(II), Zn(II) and Cd(II) can displace Cu(II) from the second Cu(II) site but not from the first strong site of human and bovine albumins (the N-terminal site). The second Cu(II) binds more strongly than the other metal ions to the second site of all three proteins, except Zn(II) binding to porcine albumin which is ca. 10 x stronger than Cu(II). The second Cu(II) site appears to be a tetragonal ¿2N, 4O¿ site.