Potentiometric and spectroscopic studies of the interaction of Cu(II) ions with the hexapeptides AcThrAlaSerHisHisLysNH2, AcThrGluAlaHisHisLysNH2, AcThrGluSerAlaHisLysNH2 and AcThrGluSerHisAlaLysNH2, models of C-terminal tail of histone H2A

Cu2+ and Ni2+ interactions with N-terminal fragments of Hpn and Hpn-like proteins from Helicobacter pylori

“…Cu 2+ coordination to the N-terminal protected fragment of Hpn (Ac-MAHHEEQHG-NH 2 ) results in six different species starting from CuH 2 L down to CuH -3 L through single deprotonation steps ( Table 2). The log K value for the reaction Cu 2+ + H 2 L ↔ CuH 2 L {logK=log β(CuH 2 L) − log β(H 2 L)} in this system (4.61) is comparable with literature data for the same type of reactions describing the formation of Cu(II)-imidazole bound complexes in the protected peptides -TESAHK-(4.47), and -TESHAK-(4.51) [28]. Lower values were observed in the case of imidazole only binding found in -FKHV-(3.60), -MKHV-(3.70), and -IKQHT-(3.74) peptides [29].…”

“…The strong shift from 578 nm to 522 nm in absorption band and changes in EPR parameters may be consistent with the participation of an additional amide nitrogen in the coordination sphere which replaces one of the imidazole nitrogens resulting in {3N − , N im } coordination. Spectroscopic data collected in Table 2 suggesting a 4N donor set are in excellent agreement with data concerning species presenting the same coordination mode in histidine containing peptides like Ac-FKHV-NH2 (λmax = 528 nm, g|| =2.185,A|| = 195G) [29], Ac-TESAHK-(λmax = 558 nm, g|| = 2.18, A|| = 198G) [28] and Ac-GGHG-OH, (g|| = 2.20, A|| =192G) [31].…”

Coordination abilities of N-terminal fragments of α-synuclein towards copper(II) ions: A combined potentiometric and spectroscopic study

“…CuH 3 L + H + ) species equal 8.18-8.39 and 7.88-7.94, respectively ( Table 2). The values of spectroscopic parameters (Tables 3 and 4 (Tables 3 and 4) suggesting that the base consuming process is deprotonation and coordination of the side chain of e-amino nitrogen atom of Lys residue in apical position [49]. In UV-Vis spectra this red shift was not observed because of overlapping the 2N complex with 3N at pH 8.5 (CuL and CuH 2 L complexes for 1-17, 1-28 and 1-39 peptides, respectively).…”

Copper effective binding with 32–62 and 94–125 peptide fragments of histone H2B

“…When chelated with bioligands, Cu(II) may result in the formation of either active [24][25][26] or non active [27] redox complexes. Indeed, Cu(II) ions interact quite efficiently with DNA bases [28,29] and several peptide models of histones H2A, H3 and H4 [30][31][32]. Our initial research described copper(II) efficient interaction with minimal peptide models of histone H2B, the blocked hexapeptides -LAHYNK- [33] and -ELAKHA- [34] (residues 80-85 and 102-107, respectively).…”