Influence of TiO2 on prebiotic thermal synthesis of the Gly-Gln polymer

Abstract

The role of the titanium dioxide (rutile and anatase) with and without room light on the thermal synthesis of the glycine-L-glutamine (Gly-Gln) polymer is described. The efficiency in percentage of polymerization with room light was increased in 6% in the presence of rutile and in 23% in the presence of anatase. The thermal synthesis in the molten state was carried out in the absence and presence of both oxides. In all cases, the vibrational spectra showed characteristic group frequencies corresponding to a polypeptide structure. No spectral differences were observed by room light effect on the polymer on rutile. However, the polymer obtained in the presence of anatase and room light shows spectral changes associated with the formation of shorter new abundant and conformationally different species compared with the original polymer. The SEM-EDX characterization of the solid phase involved in the thermal synthesis showed that the morphology of the polypeptide is different in the presence of rutile compared to anatase. The SDS-PAGE and GPC results suggest that smaller chains are formed in the presence of both oxides and the distribution of the size and weight of each polymer molecule is completely different when the condensation is performed in the presence of anatase or rutile. Nuclear magnetic resonance analyses confirmed the incorporation of both Gly and Gln residues in the polymers, with a prevalence of Gly. Both possible sequences N-GlyGln-C and N-GlnGly-C were also detected.

The Formation and Self‐Assembly of Long Prebiotic Oligomers Produced by the Condensation of Unactivated Amino Acids on Oxide Surfaces

“…[22] Because the same experimental conditions were adopted to adsorb Gly onto the other two samples, the formation of peptides on SiO 2 and TiO 2 clearly indicates that these materials exhibit catalytic activity toward the formation of poly-Gly. The catalytic activity of TiO 2 in the formation of long polypeptides was observed by Leyton et al, [21] whose work operated in a thermal polymerization regime (448-463 K) with the amino acids in the molten state. range of the Gly/TiO2 spectrum.…”

“…The absence of reactivity in the Gly/HA indicated that the temperature reached by the system during the Gly adsorption (403 K) was insufficient to allow a thermal polymerization of the amino acids, [20,21] which would be expected in the presence of trifunctional amino acids. [22] Because the same experimental conditions were adopted to adsorb Gly onto the other two samples, the formation of peptides on SiO 2 and TiO 2 clearly indicates that these materials exhibit catalytic activity toward the formation of poly-Gly.…”

Structural study and characterization of the dipeptide 2-[[5-amino-5-oxo-2-(phenylmethoxycarbonylamino) pentanoyl] amino] acetic acid by vibrational spectroscopy and DFT calculations

“…The structural and spectroscopic properties of the dipeptide 2-[ [5-amino-5-oxo-2-(phenylmethoxycarbonylamino) pentanoyl] amino] acetic acid (APPA) are important for the characterization of complex mixtures of oligopeptides that contain similar fragments, which are obtained by prebiotic thermal synthesis from aminoacetic acid (glycine) and 2-amino-4-carbamoylbutanoic acid (glutamine) [1][2][3]. Also, the phenylmethoxycarbonylamino moiety forms parts of many antiretroviral therapy (ART) drugs, which are medications that prevent retroviruses, such as HIV, from making copies of themselves [4].…”

Origins of life: From the mineral to the biochemical world

“…It was also claimed that copolymerization of glutamic acid and glycine on alumina [33] resulted in long alternate (Gly-Glu) n polymers, and that copolymerization of glutamine and glycine on titania yielded alternate (Gly-Gln) n [34]. In the same way, mixed species with equal numbers of each amino acid were observed preferentially upon thermal activation of (Glu+Arg) on montmorillonite clay [30], but this preference for alternate polymers may be due as much to the properties of the amino acids themselves as to the influence of the surface [35].…”