The free energy profiles for the condensation of glycine molecules on the sanidine surface yielding glycylglycine (Figure 1) and glycylglycylglycine as reaction products have been simulated using the ONIOM2[B3LYP/6–31 + G(d,p):MNDO] level of theory. Results indicate that the catalytic interplay between Lewis and Brønsted sites is a key factor

to favour the reactions (Rimola, et al. 2007). Additionally, theoretical results show that purely London forces between the biomolecules and the surface play a crucial role in the condensation processes because they greatly stabilize the peptide at the surface, as suggested by Orgel (Orgel, 1998). Finally, further discussion concerning the controversy between peptide polymerization vs peptide hydrolysis is click here also addressed by the explicit introduction of water molecules in the reaction process. Bernal, J. D. (1951). The Physical Basis of Life. Routledge and Kegan Paul, London. Orgel, L. E. (1998). Polymerization on the rocks: Theoretical introduction. Orig. Life Evol. Biosph., 28: 227–234. Rimola, A., Sodupe, M., and Ugliengo, P. (2007). Aluminosilicate surfaces as promoters for peptide bond formation: An assessment of Bernal’s hypothesis by ab initio methods. J. GSK2118436 cost Am. Chem. Soc., 129: 8333–8344. E-mail: piero.​ugliengo@unito.​it Origins of Genetic Information Seeking Robustness: High Neutrality and Stable Structures in Populations of RNA Sequences

Javier M. Buldú1, Jacobo Aguirre2, Susanna C. Manrubia 1Grupo de Dinámica no Lineal y Teoría del Caos. Dept. of Physics, Universidad Rey Juan Carlos, c/ Tulipán s/n, 28933 Móstoles,

Madrid, SPAIN; 2Centro de Astrobiología, INTA-CSIC. Ctra. de Ajalvir km. 4, 28850 Torrejón de Ardoz, Madrid, SPAIN High replication error rates strongly limit the length of sequences that can transmit reliable information. However, this restriction is alleviated when considering that selection acts on the phenotype: the extremely large degeneracy between genotype and phenotype spaces confers robustness (in the form of increased molecular neutrality) to RNA populations. Sets of sequences folding into the same secondary structure form neutral networks in the genome space: Chloroambucil A population of sequences can move on such networks without seeing its functionality affected, as far as the secondary structure is concerned. The adjacency matrix A ij states whether sequence i can be accessed (through a single point mutation) from sequence j, thus fully 4SC-202 describing the structure of the neutral network. In this work we study two properties of such networks that affect robustness: its areas of maximal neutrality against mutations and the minimum free energy associated to the folded state of each sequence. The topological properties of neutral networks determine (a) the time T n required to attain maximally neutral states and (b) the diversity of sequences in the population at that state.