The binding of Ni(ii) ions to terminally blocked hexapeptides derived from the metal binding -ESHH- motif of histone H2A

Nickel Ion Complexes of Amino Acids and Peptides

“…Ions Life Sci. 2, 63-108 (2007) Ala did not affect the hydrolysis reaction, substitution of the His-5 or Ser residues inhibited the reaction, supporting the important role of the last two residues in peptide bond hydrolysis [139,140]. Above pH 7 SHHK and SAHK (hydrolysis products) coordinate to Ni(II) equatorially through the imidazole of His-3, the N-terminal amino group, and the two amide nitrogens located between Ser-1 and His-3, {NH 2 , 2N Ϫ , N im }, forming 4N albumin-like square planar complexes [141].…”

“…Studies on Ni(II) coordination with the N-and C-terminal protected hexapeptides TESHHK, TASHHK, TEAHHK, TESAHK, and TESHAK [139,140], in which Ala was inserted instead of Glu, Ser, or His-4 and His-5 in the TESHHK motif, were also performed. While substitution of His-4 or Glu by Met.…”

An extremely stable Ni(II) complex derived from the hydrolytic cleavage of the C-terminal tail of histone H2A

“…Tetrapeptides SHHK-and SAHK-were synthesized in the solid phase, using the Fmoc-strategy and 1-hydroxybenzotriazole (1-HOBt)/N,N 0 -dicyclohexyl-carbodiimide (DCC) as coupling reagents, similarly with the synthesis of the hexapeptides [4,5] Their purity and identity was finally confirmed using electros pray ionization mass spectrometry (ESI-MS, Finnigan Mat TSQ 700 mass spectrometer), 1D ( 1 H-NMR) and 2D (TOCSY, total correlated spectroscopy) NMR techniques (Bruker AMX spectrometer at 400 MHz). It must be mentioned that the C-termini of the tetrapeptides were blocked by amidation, while the N-termini remained unblocked as it is expected for the real hydrolysis peptidic products [4, unpublished results] Protonation constants of both tetrapeptides and stability constants of their Ni(II) complexes as were determined from potentiometric titrations (DL50, Mettler Toledo) using the SUPERQUAD program [6].…”

“…It is well known that about 170 DNA base pairs are wrapped around a histone octamer which contains two copies of each of histones H2A, H2B, H3 and H4, forming the nucleosomes [1]. The study of the interaction of histone or histone model peptides with metal ions, and the subsequent effect on DNA of the products formed may contribute to the elucidation of the mechanism of toxicity and carcinogenicity of the latter [4,5].…”

Metal assisted peptide bond hydrolysis: Chemistry, biotechnology and toxicological implications

“…A tentative R 1 -(Ser/Thr) -Xaa-His-Zaa-R 2 sequences pattern was established, with R 1 being any amino acid sequence forming a peptide bond with the Ser or Thr residue, and R 2 being any amino acid sequence [99,100]. In these preliminary studies only a few Xaa and Zaa substitutions were investigated.…”