Nuclear magnetic resonance studies of the solution chemistry of metal complexes. 21. The complexation of zinc by glycylhistidine and alanylhistidine peptides

Copper and zinc binding properties of the N-terminal histidine-rich sequence of Haemophilus ducreyi Cu,Zn superoxide dismutase

“…2 and 3). New peaks reflecting slow exchange between the free and bound ligand, observed earlier for amide-coordinated zinc(II) complexes of Gly-His, Ala-His and Gly-His-Lys [39,40], were not detected, implying that the metal ion promoted deprotonation and coordination of amide nitrogen(s) is unlikely at pH 8.1. Although the peaks affected by the metal ion coordination are somewhat more broadened than at pH 6.6, the signals of 10 Thr and 11 Lys residues are unchanged upon zinc(II) binding, indicating that these residues are far from the metal ion.…”

Zinc(II) tweezers containing artificial peptides mimicking the active site of phosphotriesterase: The catalyzed hydrolysis of the toxic organophosphate parathion

“…From the pH or R (=[Zn 2+ ] o /[L] o )-dependence of chemical shifts, we can get more insight about that which protons are effected (thus shifted) most, i.e. gives evidence about the location of protonation/complexation sites [45,67]. The concentrations used were analogous to that was used in pH-titrations; ionic strength was kept constant at 0.1 M by using NaNO 3 .…”

“…In the case of complex 1, the extra deprotonation could be assigned to two different processes: (i) deprotonation of the coordinated water molecule or (ii) metal-promoted deprotonation of the amide. Rabenstein et al [67] showed that zinc(II)-promoted deprotonation of amide nitrogens in imidazole-containing peptides generally results in kinetically stable complexes. The chemical shifts of the protons near to the amide nitrogen are considerably altered.…”

N-terminal fragment of the anti-angiogenic human endostatin binds copper(II) with very high affinity

“…Since zinc(II) promoted deprotonation of amide nitrogens can be rarely observed and requires special H 2 N-XH-sequence [23,24], the proton releases from [ZnL] + probably result in the Table 1 Formation constants of the proton complexes of L in water and DMSO (estimated errors in paranthesis (last digit), T = 298 K, I = 0.1 M NaCl). …”