Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland.
Inorg Chem. 2010 Mar 1;49(5):2182-92. doi: 10.1021/ic902021j.
Stoichiometry, stability constants, and solution structures of copper(II) complexes of the (1-2,10-21)NPgamma (D(1)-A(2)-K(10)-R-H(12)-K-T-D-S-F-V-G-L-M(21)-NH(2)) and Ac-(1-2,10-21)NPgamma (Ac-D(1)-A(2)-K(10)-R-H(12)-K-T-D-S-F-V-G-L-M(21)-NH(2)) fragments of neuropeptide gamma were determined in aqueous solution in the pH range 2.5-10.5. The potentiometric and spectroscopic data (UV-vis, CD, EPR) show that an N-terminal Asp residue stabilizes significantly the copper(II) complexes with 1N {NH(2), beta-COO(-)} and 2N {NH(2), beta-COO(-), N(Im)} coordination modes of the (1-2,10-21)NPgamma as the result of coordination through the beta-carboxylate group. In a wide pH range of 4-9, the imidazole nitrogen of His(12) is coordinated to form a macrochelate. The (1-2,10-21)NPgamma peptide consists of 14 amino acid residues and contains an N-terminal amine group and the histidine residue, and as it is suggested, this fragment is able to bind two equivalents of copper(II) ions. The postmortem studies support the involvement of oxidative stress and the production of reactive oxygen species in neurodegenerative diseases. The susceptibility of proteins to oxidative damage is highly dependent on the specific properties of individual proteins, such as unique sequence motifs, surface accessibility, protein folding, and subcelluar localization. Metal-catalyzed oxidation of proteins is mainly a site-specific process in which one or a few amino acids at metal-binding sites on the protein are preferentially oxidized. To elucidate the products of the copper(II)-catalyzed oxidation of the (1-2,10-21)NPgamma and Ac-(1-2,10-21)NPgamma fragments of neuropeptide gamma, the liquid chromatography-mass spectrometry method and the use of Cu(II)/hydrogen peroxide as a model oxidizing system were employed. For both peptides, the oxidation of the methionine residue to methionine sulfoxide for the solutions containing peptide-hydrogen peroxide was observed. The oxidations of the histidine to 2-oxo-histidine and the methionine sulfoxide to sulfone were detected for the Cu(II)-Ac-(1-2,10-21)NPgamma-hydrogen peroxide 1:1:4 molar ratio system. Fragmentations of both peptides near the His residue were observed, supporting the participation of this (His) residue in the coordination of the copper(II) ions.
测定了神经肽γ的（1-2,10-21）NPgamma（D（1）-A（2）-K（10）-R-H（12）-K-T-D-S-F-V-G-L-M（21）-NH（2））和 Ac-（1-2,10-21）NPgamma（Ac-D（1）-A（2）-K（10）-R-H（12）-K-T-D-S-F-V-G-L-M（21）-NH（2））片段的铜（II）配合物的化学计量，稳定常数和溶液结构在 pH 值为 2.5-10.5 的水溶液中。 电位和光谱数据（UV-vis，CD，EPR）表明，由于通过β-羧酸盐基团的配位，N-末端 Asp 残基显着稳定了具有 1N{NH（2），β-COO（-）}和 2N{NH（2），β-COO（-），N（Im）}配位模式的铜（II）配合物。 在 pH 值为 4-9 的宽范围内，His（12）的咪唑氮与形成大环螯合物。 （1-2,10-21）NPgamma 肽由 14 个氨基酸残基组成，含有一个 N-末端氨基和组氨酸残基，据推测，该片段能够结合两个铜（II）离子。 尸检研究支持氧化应激和活性氧物质在神经退行性疾病中的参与。 蛋白质对氧化损伤的敏感性高度依赖于蛋白质的特定性质，例如独特的序列基序，表面可及性，蛋白质折叠和亚细胞定位。 蛋白质的金属催化氧化主要是一种位点特异性过程，其中蛋白质上金属结合位点的一个或几个氨基酸优先被氧化。 为了阐明神经肽γ的（1-2,10-21）NPgamma 和 Ac-（1-2,10-21）NPgamma 片段的铜（II）催化氧化产物，使用了液相色谱-质谱法和 Cu（II）/过氧化氢作为模型氧化系统。 对于两种肽，在含有肽-过氧化氢的溶液中观察到甲硫氨酸残基向甲硫氨酸亚砜的氧化。 检测到铜（II）-Ac-（1-2,10-21）NPgamma-过氧化氢 1:1:4 摩尔比系统中组氨酸向 2-氧代组氨酸和甲硫氨酸亚砜向砜的氧化。 在 His 残基附近观察到两种肽的片段化，支持该（His）残基参与铜（II）离子的配位。
