illite and 1-ethyl-3-(3-dimethylaminoethyl)carbodiimide

We have studied the accumulation of long oligomers of beta-amino acids on the surface of minerals using the 'polymerization on the rocks' protocol. We find that long oligopeptides of beta-glutamic acid which cannot be formed in homogeneous aqueous solution are accumulated efficiently on the surface of hydroxylapatite using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as condensing agent. The EDAC-induced oligomerization of aspartic acid on hydroxylapatite proceeds even more efficiently. Hydroxylapatite can also facilitate the ligation of the tripeptide (glu)3. The 'polymerization on the rocks' scenario is not restricted to negatively-charged amino acids. Oligoarginines are accumulated on the surface of illite using carbonyldiimidizole (CDI) as condensing agent. We find that FeS2 catalyzes the CDI-induced oligomerization of arginine, although it does not adsorb oligoarginines. These results are relevant to the formation of polypeptides on the primitive earth.

Topics: Adsorption; Arginine; Carbodiimides; Chromatography, High Pressure Liquid; Durapatite; Glutamates; Imidazoles; Minerals; Oligopeptides; Peptides

Most theories of the origin of biological organization assume that polymers with lengths in the range of 30-60 monomers are needed to make a genetic system viable. But it has not proved possible to synthesize plausibly prebiotic polymers this long by condensation in aqueous solution, because hydrolysis competes with polymerization. The potential of mineral surfaces to facilitate prebiotic polymerization was pointed out long ago. Here we describe a system that models prebiotic polymerization by the oligomerization of activated monomers--both nucleotides and amino acids. We find that whereas the reactions in solution produce only short oligomers (the longest typically being a 10-mer), the presence of mineral surfaces (montmorillonite for nucleotides, illite and hydroxylapatite for amino acids) induces the formation of oligomers up to 55 monomers long. These are formed by successive 'feedings' with the monomers; polymerization takes place on the mineral surfaces in a manner akin to solid-phase synthesis of biopolymers.

Topics: Amino Acids; Bacterial Proteins; Bentonite; Biopolymers; Carbodiimides; Durapatite; Ethyldimethylaminopropyl Carbodiimide; Evolution, Molecular; Glutamic Acid; Minerals; Models, Chemical; Oligonucleotides; Origin of Life; Poly A; Poly G; Serine Endopeptidases; Solutions