Tuning the coordination properties of multi-histidine peptides by using a tripodal scaffold: solution chemical study and catechol oxidase mimicking

Abstract

Histidine-rich tripodal peptides form unique oligonuclear complexes with copper(ii), which exhibit efficient catecholase-like activity.

Control of structure, stability and catechol oxidase activity of copper(ii) complexes by the denticity of tripodal platforms

“…Although the pK 1 of 4-nitrocatechol under these conditions is 6.8 AE 0.1, 41 i.e. unbound H4nc À is also present (l max at 432 nm 41 ), the weak breakpoint at a 1/1 [H 2 4nc]/[Cu 3 H Àx L 2 ] tot ratio (inset in Fig. 10) can be clearly seen.…”

“…Identical observations were reported in the literature related to MALDI-TOF MS studies of many copper(II) complexes, formed with cyclen/cyclam derivatives, 38 some pseudo-peptides 39 and peptides. 40,41 Accordingly, reduced copper centers were observed for the trinuclear species too. Its MALDI-TOF MS spectrum (Fig.…”

“…13 In order to understand the activation of dioxygen by metalloenzymes a large number of biomimetic models of catechol oxidase have been studied. 14,43 Catechol oxidases are type 3 copper enzymes; 44,45 therefore mainly dinuclear complexes were used, [46][47][48][49][50][51] but several mono- 52,53 and trinuclear 13,41,54 species were also reported to have important catechol oxidase activity. Table 3 Spectroscopic parameters of the different copper(II) complexes observed, with estimated errors in parentheses (last digit) a Trinuclear complex spectra were described as the sum of mononuclear and broad singlet type spectra for which only g o values could be determined.…”

Investigation of dioxygen activation by copper(ii)–iminate/aminate complexes

“…For example, a mechanism of dioxygen activation that has been proposed for quercetinase, 56 a copper dioxygenase which breaks down quercetin and other flavonols to depsides, is its direct reaction with the substrate's radical. 57 Studies on catechol [58][59][60] and p-semiquinone 12, 61 radical metal-complexes, models of oxidases, proved that dioxygen is activated by the ligand's radical and thus, support the proposed mechanism for quercetinase.…”

Increasing the histidine ‘density’ in tripodal peptides by gradual N -functionalization of tris (2-aminoethyl)amine (tren) with l -histidyl units: The effect on zinc(II) complexes

“…Tripodal peptidomimetics have been receiving increasing interest in the last decades in order to create chiral receptor molecules [1,2], triple helical biomimetic materials [3], peptide-like dendrimers for e.g. drug delivery [4], organic catalysts [4] or metal ion chelators [5][6][7][8][9][10][11][12]. The metal ion binding properties of tripodal peptidomimetics can differ significantly from those of linear peptides.…”