title: 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.
abstract: 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.
  
  
  
  The [M+(Ag)n ](+) complexes are prepared and characterized using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS).
  
  
  
  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 [M2 +(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.
  
  
  
  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.
authors.affiliation: Atomic & Molecular Physics Division, Physics Group, Bhabha Atomic Research Centre, Trombay, Mumbai, 400 085, India.
authors.forename: Shyam L
authors.initials: SL
authors.lastname: Gupta
authors.affiliation: Atomic & Molecular Physics Division, Physics Group, Bhabha Atomic Research Centre, Trombay, Mumbai, 400 085, India.
authors.forename: Vikas
authors.initials: V
authors.lastname: Dhiman
authors.affiliation: Atomic & Molecular Physics Division, Physics Group, Bhabha Atomic Research Centre, Trombay, Mumbai, 400 085, India.
authors.forename: T
authors.initials: T
authors.lastname: Jayasekharan
authors.affiliation: Atomic & Molecular Physics Division, Physics Group, Bhabha Atomic Research Centre, Trombay, Mumbai, 400 085, India.
authors.forename: N K
authors.initials: NK
authors.lastname: Sahoo
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D001839:Bombesin / Q000737:chemistry; D001920:Bradykinin / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D008958:Models, Molecular; D009496:Neurotensin / Q000737:chemistry; D010121:Oxytocin / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013004:Somatostatin / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D014667:Vasopressins / Q000737:chemistry
chemical_list: D010455:Peptides; D014667:Vasopressins; D009496:Neurotensin; D012834:Silver; D010121:Oxytocin; D013004:Somatostatin; D001839:Bombesin; D001920:Bradykinin