Conformational transition of acidic peptides exposed to minerals in suspension

Mineral surfaces probably participated in the chemical processes which led to life in the primitive oceans. The ordered conformations of simple acidic peptides exposed to insoluble minerals are described. Alternating poly(Glu -Leu) adopts a random coil conformation in water due to charge repulsion. T he polypeptide extracts cations from insoluble crystalline CdS or molybdenu m and adopts an ordered conformation. CdS leads to the formation of beta-sh eets whereas molybdenum leads to alpha-helices, Peptides with at least 10-a mino acids are necessary to exhibit a significative adsorption onto the sur face, Under the same conditions, montmorillonite adsorbs the polypeptide bu t does not induce any conformational change.