title: Characterization of the antioxidative activity of novel nontoxic neuropeptides by using capillary electrophoresis.
abstract: In the present study, we have monitored the oxidation process of novel nontoxic neuropeptides and determined its rate constants, which describe the antioxidative potential of the peptides. A capillary electrophoretic method was implemented which ensures the simultaneity of analysis of reactants and products in a short time of analysis. The rate constants of oxidation of the four novel peptides, 4-methoxy-L-tyrosinyl-gamma-L-glutamyl-L-cysteinyl-glycine (UPF1), D-serinyl-gamma-L-glutamyl-L-cysteinyl-glycine (UPF6), 4-methoxy-L-tyrosinyl-alpha-L-glutamyl-L-cysteinyl-glycine and D-serinyl-alpha-L-glutamyl-L-cysteinyl-glycine, designed by us, were compared with those of oxidation of glutathione (reduced glutathione) by using capillary electrophoresis. The second-order rate constants were similar for all peptides if the oxidation was carried out with hydrogen peroxide (k(II) = 0.208 - 0.236 x 10(3)/M.min). The rate constants were also determined for the mixtures of peptides. When the oxidation is caused by hydroxyl radical (OH*), the gamma-glutamate containing peptides (UPF1 and UPF6) exhibited two to four times higher antioxidative activity (k(II) = 4.428 and 2.152 x 10(3)/M.min, respectively). The results suggest that the antioxidative potential of the peptides studied is not determined by the formation of disulphide bridge alone.
authors.affiliation: Department of Chemistry, Tallinn University of Technology, Estonia. merike@chemnet.ee
authors.forename: Merike
authors.initials: M
authors.lastname: Vaher
authors.forename: Säde
authors.initials: S
authors.lastname: Viirlaid
authors.forename: Kersti
authors.initials: K
authors.lastname: Ehrlich
authors.forename: Riina
authors.initials: R
authors.lastname: Mahlapuu
authors.forename: Jüri
authors.initials: J
authors.lastname: Jarvet
authors.forename: Ursel
authors.initials: U
authors.lastname: Soomets
authors.forename: Mihkel
authors.initials: M
authors.lastname: Kaljurand
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D019075:Electrophoresis, Capillary; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D009479:Neuropeptides / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D000975:Antioxidants; D009479:Neuropeptides; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide