A Pentapeptide with Tyrosine Moiety as Fluorescent Chemosensor for Selective Nanomolar-Level Detection of Copper(II) Ions

Abstract

Herein, we have investigated principally with the use of UV and fluorescence (steady-state and time-resolved) spectroscopy the interactions between selected pentapeptides with tyrosine residue (EYHHQ, EHYHQ, EHHQY, and KYHHE) and various metal ions (Cu2+, Mn2+, Co2+, Ni2+, Zn2+, Cr3+, Cd2+, Ag+, Pb2+, Sr2+, Ba2+, Ca2+, Mg2+, Al3+, Fe2+, and Ga3+) in order to establish the relationship between the position of a tyrosine residue in the peptide sequence and the metal ion-binding properties. Among the peptides studied, EHYHQ was evaluated as an efficient and selective ligand for developing a chemosensor for the detection of copper(II) ions. While significant fluorescence emission quenching was observed for that peptide in the presence of Cu2+ cations, other metal cations used at the same and at considerably higher concentrations caused a negligible change of the fluorescence emission spectrum, indicating a high selectivity of EHYHQ for Cu2+ ions. Under optimum conditions, fluorescence intensity was inversely proportional to the concentration of Cu2+ ions. The limit of detection of Cu2+ ions with the use of EHYHQ was determined at the level of 26.6 nM. The binding stoichiometry of the complexes of the studied peptides with Cu2+ ions was evaluated spectrophotometrically and fluorimetrically (as in the case of EHYHQ confirmed by mass spectrometry) and found to be 1:2 (Cu2+-peptide) for all the investigated systems. Furthermore, the stability constant (K) values of these complexes were determined. The reversibility of the proposed Cu2+ ions sensor was confirmed, the pH range where the sensor acts was determined, while its analytical performance was compared with some other reported recently fluorescent sensors. The mechanism of the interactions between EHYHQ and Cu2+ was proposed on the basis of NMR spectroscopy investigations.

Veni, Vidi, Vici: Immobilized Peptide-Based Conjugates as Tools for Capture, Analysis, and Transformation

“…The affinity of peptides towards metal ions is a well-known and broadly studied phenomenon [132]. The complexation of metal ions may involve peptide-based ligands formed directly from unmodified peptide sequences [133][134][135] resembling metalloenzyme active centers [136] or structural element-like zinc fingers [137], peptides containing nonproteinaceous amino acids or modified by the attachment of high affinity motifs to functional groups in peptide side chains [138]. The organization of peptide primary and secondary structures offers a unique opportunity to arrange and orient coordination spheres for metal ions [139].…”

Interactions of Aβ1-42 Peptide and Its Three Fragments (Aβ8-12, Aβ8-13, and Aβ5-16) with Selected Nonsteroidal Drugs and Compounds of Natural Origin

“…Human amyloid β protein fragment 1-42 (95%, by HPLC) was obtained from AnaSpec Inc. (CA, USA) and used as received. Its shorter fragments chosen for the experiments (Aβ8-12, Aβ8-13, and Aβ5- 16) were synthesized [36] and chromatographically purified [37] using procedures described previously. The peptides were then characterized using mass spectrometry.…”

“…The peptides were then characterized using mass spectrometry. The concentration of the probes was confirmed spectrophotometrically using Perkin Elmer Lambda 650 UV/Vis spectrophotometer on the basis of the measurement of absorbance of tyrosine at 280 nm (ε280 = 1280 M −1 cm −1 ) [37]. Aspirin (acetylsalicylic acid, >95%), ibuprofen (α-methyl-4-(isobutyl)phenylacetic acid, 99%), anabasine (neonicotine, >97%), and epinephrine (adrenaline, >95%) were obtained from Sigma Aldrich (Poland) and used as purchased.…”

“…The peptides were then characterized using mass spectrometry. The concentration of the probes was confirmed spectrophotometrically using Perkin Elmer Lambda 650 UV/Vis spectrophotometer on the basis of the measurement of absorbance of tyrosine at 280 nm (ε 280 = 1280 M −1 cm −1 ) [37].…”

A New Cellulose-Based Fluorescent Probe for Specific and Sensitive Detection of Cu2+ and Its Applications in the Analysis of Environmental Water

“…These conventional methods have some problems such as expensive testing equipment, difficult operations and long detection time. Compared with the above methods, fluorescence spectroscopy can well overcome the above defects and is widely used in the detection of Cu 2+ [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Hence, it is necessary and significant to develop fluorescent probes for monitoring Cu 2+ .…”