The subsequent evolution of life was in a great extent driven by the competition for access to hydrogen. Decline of the primary sources of hydrogen mentioned above made life to switch for the hydrogen compounds such as H2S, CH4, NH3, and at last, H2O in the oxygenic photosynthesis. The succession and degree of involvement of these simple molecules into early metabolic evolution could correlate to the energy required for breaking their

chemical bonds in the conditions of early Earth. This concept helps to understand the historical causes of the atmosphere chemistry, in particular, the high content of nitrogen and oxygen as the byproducts of hydrogen metabolism. Early kinds of biochemistry, once established, have been saved throughout of this website the later history of life via addition of complementary metabolic modules in respose to the irreversible changes of the environment. This was the major driving factor of evolution towards the higher biological complexity. Fedonkin, M. A. (2008), Ancient biosphere: The origin, trends and events. Russian Journal of Earth Sciences, 10, ES1006, doi:10.2205/2007ES000252. Hengeveld, R. and Fedonkin, M. A. (2007) Bootstrapping buy Bucladesine the energy flow in the beginning of life. Acta Biotheoretica, 55: 181–226. E-mail: mfedon@paleo.​ru

Unevolved Proteins from a Model Synthetic Proteome Are Functionally Active in vivo Michael A. Fisher, Luke H. Bradley, Sara R. Viola, Michael H. Hecht The polypeptides comprising the evolved proteomes of modern-day organisms are adequately functional macromolecules. The goal of our work is to assess the functional activity of unevolved protein sequence space—polypeptides that have not undergone evolutionary selection. To this end, we have used the binary code strategy for protein design to generate a large and combinatorially diverse collection of synthetic

PtdIns(3,4)P2 proteins. The binary code strategy for protein design enables the construction of synthetic libraries of folded proteins by specifying the locations of polar and nonpolar amino acids along a polypeptide chain in accordance with the periodicity of a desired element of secondary structure (alpha helix or beta sheet). However, VX809 because the binary code does not explicitly specify the identities of each polar or nonpolar side chain, this strategy facilitates enormous combinatorial diversity. Our target protein structure is a 102-residue four-helix bundle and the library is constructed at the gene level. We cloned our library of fully-assembled synthetic genes into an expression vector, generating a library of approximately 1.5 × 106 clones. To assess the functional potential of this model synthetic proteome, we tested whether de novo proteins from our library can provide biological activities essential for cell growth. We expressed the library of synthetic proteins in a series of E. coli single gene deletion strains that form colonies on rich media but not on M9-glucose minimal media (conditional auxotrophs).