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Iron(III) Oxide Nanoparticles as Catalysts for the Formation of Linear Glycine Peptides

2016; Wiley; Volume: 2017; Issue: 1 Linguagem: Inglês

10.1002/ejic.201601296

1099-0682

Thomas Georgelin, Mariame Akouche, Maguy Jaber, Yuriy Sakhno, Lucrèce Mathéron, Frédéric Fournier, Christophe Méthivier, Gianmario Martra, Jean‐François Lambert,

Enzyme Catalysis and Immobilization

We have studied the behavior upon thermal activation of glycine adsorbed on three well‐characterized Fe 3+ oxide nanoparticle phases, maghemite, hematite, and akaganeite. The behavior of the adsorbed molecules and of the nanoparticle surfaces was monitored by four main experimental techniques, thermogravimetric analysis/differential thermal analysis (TGA/DTA), XPS, infrared spectroscopy (IR), and mass spectrometry. Glycine polymerizes by peptide bond formation in the 180–190 °C temperature range, which is somewhat higher than on previously studied oxides such as silica or alumina, giving mostly short linear peptides. At slightly higher temperatures, under an inert gas, the iron oxyhydroxides act as stoichiometric oxidants and cause oxidative degradation of the peptides formed in the previous step while they are reduced to FeO; under air, dioxygen causes reoxidation of the nanoparticle surfaces so that the overall effect is a catalytic oxidation by O 2 . While the direct formation of linear peptides may be beneficial to the growth of prebiotic complexity, the redox reactivity of the supports limits the temperature stability range of the oligopeptides.