In the recent decades, antibacterial peptides have occupied a strategic position for pharmaceutical drug applications and became subject of intense research activities since they are used to strengthen the immune system of all living organisms by protecting them from pathogenic bacteria. This work proposes a simple and easy statistical/computational method through a peptide polarity index measure by which an antibacterial peptide subgroup can be efficiently identified, that is, characterized by a high toxicity to bacterial membranes but presents a low toxicity to mammal cells. These peptides also have the feature not to adopt to an alpha-helicoidal structure in aqueous solution. The double-blind test carried out to the whole Antimicrobial Peptide Database (November 2011) showed an accuracy of 90% applying the polarity index method for the identification of such antibacterial peptide groups.

Clay minerals are considered important to chemical evolution processes due to their properties, ancient origin, and wide distribution. To extend the knowledge of their role in the prebiotic epoch, the adsorption sites of adenine, adenosine, AMP, ADP, ATP, Poly A, uracil, uridine, UMP, UDP, UTP and Poly U on sodium montmorillonite are investigated. X-ray diffraction, ultraviolet and infrared spectroscopy studies indicate that these molecules distribute into the interlamellar channel and the edge of the clay crystals. Monomers are adsorbed predominantly in the interlamellar channel, whereas polymers adsorb along the crystal edges. Such behavior is discussed mainly in terms of bulk pH, pK(a) of the adsorbate, and Van der Waals interactions.

A hydrothermal system is an environment where there is a flow of hot fluids beneath and up to the surface of the Earth. Hydrothermal vents are systems whose heat source is the underlying magma or hot water generated by convection currents due to high thermal gradients. Hydrothermal fossil deposits have also been recognized in impact craters. Besides Earth, the other place in the Solar System that shows evidence of past impact-induced hydrothermal systems is Mars. The circulation of hydrothermal solutions and interaction with country rocks leads to the precipitation of different mineral phases. In fact, hydrothermal vents, due to their characteristics (redox potential, abundance of organic matter and the presence of certain minerals), have been proposed as places where chemical evolution could have occurred. In this article, a review of hydrothermal environments (submarine, subaerial and impact-induced) and their advantages and disadvantages as primitive environments is presented. Thus far, the synthesis of organic compounds in simulation experiments has been achieved, although the role of prebiotic processes in these environments is still ill-defined. The conditions accompanying white vents are perhaps the best suited for the synthesis of organic molecules; however, this synthesis could have also occurred around black vents, where favorable temperature gradients are present.

Abstract. 0 2 -free aqueous solutions of 0.05 mol dm -3 rmmonium bicarbonate were studied after receiving vnrious doses of so Co gammas (0.001-170 Mrd) or krd pulses of 10 MeV electrons. Formate, oxalate, formaldehyde and an unidentified polymer (M W 14000-16000 daltons) were found to be the main radiolytic products. A large initial yield of formate in the Y-radiolysis, G(HC00 -) = 2.2, is due to the reaction CO* + HCO7 t HC00~ + CO3. The efficiency of organic synthesis within the large dose range studied is low and is explained by efficient pathways to the reformation of bicarbonate, where the reaction