FROM AMINO-ACIDS TO PREBIOTIC ACTIVE PEPTIDES - A CHEMICAL RECONSTITUTION

Primitive life can be schematically described as organic molecules pro cessed by liquid water. Amino acids were most likely available on the primitive Earth, home-made from the primitive atmosphere or in hydroth ermal vents. Import of extraterrestrial amino acids may represent an a lternative supply. Experimental evidence is given for selective conden sation of amino acids driven by the hydrolytic power of liquid water. When hydrophobic and hydrophilic amino acids are forced to coexist wit hin the same chain in liquid water, the duality generates interesting topologies such as stereoselective and thermostable beta-pleated sheet structures. Polycationic alternating peptides containing lysyl and hy drophobic residues strongly accelerate the hydrolysis of oligoribonucl eotides. The beta-sheet geometry plays an determinant role in the obse rved chemical activity, as in contemporary enzymes. Beta-sheet forming peptide sequences may represent a support for primordial information amplification.