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Analysis of argentinated peptide complexes using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry: Peptide = oxytocin, arg 8 ‐vasopressin, bradykinin, bombesin, somatostatin, neurotensin
Author(s) -
Gupta Shyam L.,
Dhiman Vikas,
Jayasekharan T.,
Sahoo N. K.
Publication year - 2016
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.7562
Subject(s) - bombesin , chemistry , peptide , vasopressin , neurotensin , somatostatin , bradykinin , neuropeptide , peptide hormone , oxytocin , mass spectrometry , receptor , biochemistry , chromatography , medicine
Rationale The increased use of silver nanoparticles (AgNPs) for various biological applications, and over‐expression of various peptide receptors in different tumors/cancer cells, necessitate the need for dedicated investigations on the intrinsic binding ability of Ag with various biologically important peptides for better understanding of AgNPs‐peptide interactions and for the future development of contrasting agents as well as drugs for imaging/biomedical applications. Methods The [M+(Ag) n ] + complexes are prepared and characterized using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS). Results Silver complexes of the peptides [M+(Ag) n ] + , where M = oxytocin, arg 8 ‐vasopressin, bradykinin, bombesin, somatostatin, and neurotensin, have been investigated for their intrinsic Ag + ‐binding ability. Unusual binding of up to seven Ag + with these small peptides is observed. The mass spectra show n = 1–5 for bombesin and somatostatin, n = 1–6 for bradykinin and arg 8 ‐vasopressin, and n = 1–7 for oxytocin and neurotensin. In addition, oxytocin and arg 8 ‐vasopressin show the formation of dimers and their complexes [M 2 +(Ag) n ] + with n = 1–8 and n = 1–5, respectively. The possible amino acid residues responsible for Ag + binding in each peptide have been identified on the basis of density functional theory (DFT)‐calculated binding energy values of Ag + towards individual amino acids. Conclusions Mass spectrometric evidence indicates that the peptides, viz ., oxytocin, arg 8 ‐vasopressin, bradykinin, bombesin, somatostatin, and neurotensin, show greater affinity for Ag + . Hence, they may be used as carriers for AgNPs in targeted drug delivery as well as an alternative for iodinated contrasting agents in dual energy X‐ray imaging techniques. Radio‐labeled Ag with these peptides can also be used in radio‐pharmaceuticals for diagnostic and therapeutic applications. Copyright © 2016 John Wiley & Sons, Ltd.