N‐Terminal Cu‐Binding Motifs (Xxx‐Zzz‐His, Xxx‐His) and Their Derivatives: Chemistry, Biology and Medicinal Applications

Abstract

Peptides and proteins with N-terminal amino acid sequences NH -Xxx-His (XH) and NH -Xxx-Zzz-His (XZH) form well-established high-affinity Cu -complexes. Key examples are Asp-Ala-His (in serum albumin) and Gly-His-Lys, the wound healing factor. This opens a straightforward way to add a high-affinity Cu -binding site to almost any peptide or protein, by chemical or recombinant approaches. Thus, these motifs, NH -Xxx-Zzz-His in particular, have been used to equip peptides and proteins with a multitude of functions based on the redox activity of Cu, including nuclease, protease, glycosidase, or oxygen activation properties, useful in anticancer or antimicrobial drugs. More recent research suggests novel biological functions, mainly based on the redox inertness of Cu in XZH, like PET imaging (with Cu), chelation therapies (for instance in Alzheimer's disease and other types of neurodegeneration), antioxidant units, Cu transporters and activation of biological functions by strong Cu binding. This Review gives an overview of the chemical properties of Cu-XH and -XZH motifs and discusses the pros and cons of the vastly different biological applications, and how they could be improved depending on the application.

The Sub‐picomolar Cu2+ Dissociation Constant of Human Serum Albumin

“…The existence of the minor CuHL complex is ascertained from the absorption trace at 685 nm; the absence of a corresponding signal in CD spectra is indicative of a macroloop structure, with the Cu 2+ ion coordinated to the N‐terminal amine and an imidazole nitrogen . The CuH −1 L and CuH −2 L species share all spectroscopic properties, both being typical ATCUN complexes isostructural with the N‐terminal site of HSA . The p K a of transition from CuH −1 L to CuH −2 L is consistent with the deprotonation of the nonbonding terminal carboxylate, elevated due to the decrease in the complex charge compared with the free peptide.…”

“…Human serum albumin (HSA) is the most abundant serum protein in the blood and acts as a carrier for numerous cargo molecules including lipids, hormones, metabolites, drugs and essential and toxic metals . It also contains an N‐terminal site (NTS) for binding divalent copper ions, which contains the amino‐terminal copper and nickel (ATCUN) motif, comprising a H 2 N‐Xaa‐Yaa‐His sequence . Albumin is a part of an elaborate copper‐trafficking machinery consisting of two groups of copper carriers .…”

Human Antimicrobial Peptide Hepcidin 25-Induced Apoptosis in Candida albicans

“…Moreover, adding an N-terminal ATCUN motif to different AMPs can enhance the activity of these peptides by inducing ROS formation [46]. Moreover, previous studies also indicated that the Cu(II)-ATCUN complex can damage DNA, RNA, proteins and lipids because it induces ROS generation [72][73][74]. Therefore, ROS are important for AMPs to killing of microbial pathogens [75][76][77][78] and are possibly generated through a Fenton-like reaction involving the Cu(II)-ATCUN complex [74,79].…”

Análogos sintéticos da cheferina I: interação com íons metálicos divalentes e o seu efeito na internalização celular e nas atividades anticandida e candidacida

“…Libardo e colaboradores (2014) adicionaram às sequências dos peptídeos anoplin (GLLKRIKTLL 10 -NH 2 ), pró-apoptótico (PAP; KLAKLAKKLAKLAK 14 -NH 2 ) e shbuforin (RAGLQFPVGRVHRLLRK 17 -NH 2 ) os motivos ATCUN ("DAH" ou "GGH" ou induz a produção de EROs e danos à membrana mitocondrial/fosfolipídios, devido ao motivo ATCUN "DSH" em sua sequência peptídica que possibilita a coordenação de tais íons em geometria quadrada planar distorcida (HARFORD;SARKAR, 1997;MELINO et al, 2014;GONZALEZ et al, 2018). De fato, elevada atividade pró-oxidante da Hst 5 foi observada quando em presença de íons Cu 2+ (CABRAS et al, 2007).…”

“…Atualmente, o estudo da possibilidade de aumentar a atividade e estabilidade de AMPs na presença de íons metálicos divalentes e a procura por sondas intracelulares destes íons, principalmente íons Cu 2+ (associado à angiogênese e progressão tumoralvide item 4.2.1. ), vem sendo intensificados (LIBARDO et al, 2014;DENOYER et al, 2015;GONZALEZ et al, 2018;ŁOBODA; ROWIŃSKA-ZYREK, 2018). Da mesma forma, a doença de Alzheimer também tem sido associada a um desequilíbrio destes íons, em especial Zn 2+ , Fe 3+ e Cu 2+ , que são acumulados nas placas amiloides depositadas no cérebro através da coordenação com o peptídeo Aβ (CHEN et al, 2006;HU et al, 2016;KEPP, 2017).…”