title: Letter: Mass spectrometric evidence for iron binding to the neuroprotective peptide NAP and its Cys5 mutant.
abstract: The NAP peptide (H(2)N-(1)NAPVSIPQ(8)-CONH(2)) is a truncated version of the activity-dependent neuroprotective protein. Its neuroprotective activities consist of the inhibition of Aβ(25-35) and Aβ(1-40) fibrillogenesis as well as protection against Aβ-induced neurotoxicity and prevention of microtubule disruption associated with Alzheimer's disease. Therefore, we synthesized NAP and its mutant peptide with the sequence: H(2)N-(1)NAPVCIPQ(8)-COOH (NAPCOH), by replacing serine S(5) with cysteine C(5). Both native and mutant peptides were further used to study their interaction with iron ions. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry, Fourier transform infrared spectroscopy and also atomic force microscopy were used to probe Fe(3+) binding to both peptides. Contrary to the expected results, the investigated peptides underwent different oxidation processes, with resultant reduced Fe(2+) ions. These ions, and not the original Fe(3+) ions, were found to bind to each of non-oxidized peptides.
authors.affiliation: Research Department, Faculty of Chemistry, "Al. I. Cuza" University, 11 Carol I, Iasi-700506, Romania. catalina.ciobanu@uaic.ro.
authors.forename: Catalina-Ionica
authors.initials: CI
authors.lastname: Ciobanu
authors.affiliation: Faculty of Chemistry, Al. I. Cuza University of Iasi, 11 Carol I, Iasi -700506, Romania. rallstef@gmail.com.
authors.forename: Raluca
authors.initials: R
authors.lastname: Stefanescu
authors.affiliation: Research Centre for Oenology, Romanian Academy, 8 Carol I, Iasi - 700505, Romania. niculaua@gmail.com.
authors.forename: Marius
authors.initials: M
authors.lastname: Niculaua
authors.affiliation: Faculty of Physics, "Al. I. Cuza" University, 11 Carol I, Iasi-700506, Romania. teslaruteodora@yahoo.com.
authors.forename: Teodora
authors.initials: T
authors.lastname: Teslaru
authors.affiliation: Faculty of Chemistry, Al. I. Cuza University of Iasi, 11 Carol I, Iasi -700506, Romania. robert.gradinaru@uaic.ro.
authors.forename: Robert
authors.initials: R
authors.lastname: Gradinaru
authors.affiliation: Faculty of Chemistry, Al. I. Cuza University of Iasi, 11 Carol I, Iasi -700506, Romania. gabidr@uaic.ro.
authors.forename: Gabi
authors.initials: G
authors.lastname: Drochioiu
mesh_terms: D000595:Amino Acid Sequence; D003545:Cysteine; D006801:Humans; D007477:Ions; D007501:Iron; D010455:Peptides; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D007477:Ions; D010455:Peptides; D007501:Iron; D003545:Cysteine