Binding of nickel(II) and copper(II) to the N-terminal sequence of human protamine HP2.
A potentiometric and spectroscopic (UV/vis and CD) study of Cu(II) and Ni(II) binding to the N-terminal pentadecapeptide of human protamine HP2 (HP2(1-15)) was performed. The results indicate that the N-terminal tripeptide motif Arg-Thr-His is the exclusive binding site for both metal ions at a metal to HP2(1-15) molar ratio not higher than 1. The very high value of protonation-corrected stability constant (log *K) for Ni(II)-HP2(1-15) complex, -19.29, indicates that HP2 has the potential to sequester Ni(II) from other peptide and protein carriers, including albumin. The same is likely for Cu(II) (log *K = -13.13). The CD spectra of Cu(II) and Ni(II) complexes of HP2(1-15) indicate that the N-terminal metal binding affects the overall conformation of the peptide that, in turn, may alter interaction of HP2 with DNA. These results imply HP2 as a likely target for the toxic metals Ni(II) and Cu(II).
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Laboratory of Comparative Carcinogenesis, National Cancer Institute, FCRDC, Frederick, Maryland 21702, USA.
Jezowska-Bojczuk
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Kasprzak
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D000595:Amino Acid Sequence; D003300:Copper / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009532:Nickel / Q000378:metabolism*; D011479:Protamines / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation
D011479:Protamines; D003300:Copper; D009532:Nickel