Peptides Derived from Angiogenin Regulate Cellular Copper Uptake

Abstract

The angiogenin protein (ANG) is one of the most potent endogenous angiogenic factors. In this work we characterized by means of potentiometric, spectroscopic and voltammetric techniques, the copper complex species formed with peptide fragments derived from the N-terminal domain of the protein, encompassing the sequence 1-17 and having free amino, Ang1-17, or acetylated N-terminus group, AcAng1-17, so to explore the role of amino group in metal binding and cellular copper uptake. The obtained data show that amino group is the main copper anchoring site for Ang1-17. The affinity constant values, metal coordination geometry and complexes redox-potentials strongly depend, for both peptides, on the number of copper equivalents added. Confocal laser scanning microscope analysis on neuroblastoma cells showed that in the presence of one equivalent of copper ion, the free amino Ang1-17 increases cellular copper uptake while the acetylated AcAng1-17 strongly decreases the intracellular metal level. The activity of peptides was also compared to that of the protein normally present in the plasma (wtANG) as well as to the recombinant form (rANG) most commonly used in literature experiments. The two protein isoforms bind copper ions but with a different coordination environment. Confocal laser scanning microscope data showed that the wtANG induces a strong increase in intracellular copper compared to control while the rANG decreases the copper signal inside cells. These data demonstrate the relevance of copper complexes’ geometry to modulate peptides’ activity and show that wtANG, normally present in the plasma, can affect cellular copper uptake.

BDNF- and VEGF-Responsive Stimulus to an NGF Mimic Cyclic Peptide with Copper Ionophore Capability and Ctr1/CCS-Driven Signaling

“…Moreover, g ∥ (2.305) and A ∥ (169 × 10 –4 cm –1 ) values further support the copper coordination mode suggested for [CuL]. The lower hyperfine coupling constant as well as the slightly higher g ∥ -value compared with similar systems − can be attributed to a distortion of the coordination environment from planarity. Furthermore, the A ∥ value of [CuL] is higher than that found for the analogous species of the acetylated linear peptide (i.e., A ∥ = 158 × 10 –4 cm –1 ) likely cyclization brings the two histidine residues closer to one another, thus favoring the formation of a macrochelate.…”

Copper(II) Complexes with Carnosine Conjugates of Hyaluronic Acids at Different Dipeptide Loading Percentages Behave as Multiple SOD Mimics and Stimulate Nrf2 Translocation and Antioxidant Response in In Vitro Inflammatory Model

“…Such ESR parameters are typical of the coordination of at least two nitrogen atoms. Hence, the blue-shift can be attributed to a new chromophore arising from the binding of a further nitrogen atom, which occurs with the assistance of carboxylate oxygen atoms, and featuring by a {2N Im , 2O COO } coordination mode [ 120 , 121 ]. This metal complex becomes the predominant complex at a pH value of 7.9, where another complex was also found.…”

Copper metabolism and cuproptosis in human malignancies: Unraveling the complex interplay for therapeutic insights

“…It has a significant impact on ribonucleolytic activity translocating into the nucleus and binding to actin, thus leading to the proliferation and metastasis of transformed tumor cells. It has also been exhibited that copper ion binds to angiogenin, initiating migration and proliferation [ 48 , 50 , 51 ].…”