Binding of Cu⁺ and Cu²⁺ with peptides: Peptides = oxytocin, Arg⁸‐vasopressin, bradykinin, angiotensin‐I, substance‐P, somatostatin, and neurotensin

Abstract

The intrinsic binding ability of 7 natural peptides (oxytocin, arg -vasopressin, bradykinin, angiotensin-I, substance-P, somatostatin, and neurotensin) with copper in 2 different oxidation states (Cu ) derived from different Cu precursor sources have been investigated for their charge-dependent binding characteristics. The peptide-Cu complexes, [M - (n-1)H + nCu ] and [M - (2n-1)H + nCu ], are prepared/generated by the reaction of peptides with CuI solution/Cu-target and CuSO solution and are analyzed by using matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry. The MALDI mass spectra of both [M - (n-1)H + nCu ] and [M - (2n-1)H + nCu ] complexes show no mass shift due to the loss of ─H atoms in the main chain ─NH of these peptides by Cu and Cu deprotonation. The measured m/z value indicates the reduction of Cu oxidation state into Cu during MALDI processes. The number and relative abundance of Cu bound to the peptides are greater compared with the Cu bound peptides. Oxytocin, arg -vasopressin, bradykinin, substance-P, and somatostatin show the binding of 5Cu , and angiotensin-I and neurotensin show the binding of 7Cu from both CuI and Cu targets, while bradykinin shows the binding of 2Cu , oxytocin, arg -vasopressin, angiotensin-I, and substance-P; somatostatin shows the binding of 3Cu ; and neurotensin shows 4Cu binding. The binding of more Cu with these small peptides signifies that the bonding characteristics of both Cu and Cu are different. The amino acid residues responsible for the binding of both Cu and Cu in these peptides have been identified based on the density functional theory computed binding energy values of Cu and the fragment transformation method predicted binding preference of Cu for individual amino acids.

Molecular Basis of Mammalian Odor Discrimination: A Status Report

“…Notably, more hindered thiols such as t -BuSCH 2 SH and EtSCHMeSH showed reduced activity toward MOR244-3 in the presence of copper. Both Cu­(I) and Cu­(II) species should be available to ORs given the known reducing environment within cells and the demonstrated binding ability of both Cu­(I) and Cu­(II) with peptides …”

“…Both Cu(I) and Cu(II) species should be available to ORs given the known reducing environment within cells and the demonstrated binding ability of both Cu(I) and Cu(II) with peptides. 120 Because cysteine, histidine, and methionine frequently coordinate copper in cuproenzymes, site-directed mutagenesis experiments were performed with MOR244-3, mutating these three amino acids. Complete loss of response to MTMT was observed in some cases, while response to nonsulfurous ligands was maintained, suggesting that only copper/ligand binding was disrupted.…”

Enhancement of Hydrogen Productions by Accelerating Electron-Transfers of Sulfur Defects in the CuS@CuGaS2 Heterojunction Photocatalysts

“…For example, Cu 2−x S is very different from Cu 2−x O but shows a similar structure to Cu 2−x Se (klockmannite) [9]. CuS compound is paramagnetic due to the 3d 9 electron arrangement, and some studies have reported that all Cu atoms in CuS have an oxidation state of Cu + based on XPS results [10]. However, it can be attributed to (Cu + ) 2 Cu 2+ S 2 with both Cu(I) and Cu(II) in the XRD crystal structure results [11].…”

What Is the Correlation between Preeclampsia and Cancer? The Important Role of Tachykinins and Transition Metal Ions

“…Met-11, Leu-10 and Lys-3 were found on the anchoring sites for Cu(II) in SP, according to calculated binding energies determined by DFT. Noteworthily, the pH of the studied solutions was in the range of 2 to 3 [ 145 ]. It was also suggested that SP is not able to bind Cu(II) ions selectively in a solution environment at a physiological pH.…”