Recherches sur la formation et la transformation des esters LXXXIII [1]. Réactions de condensation et/ou de phosphorylation,en solution aqueuse,de divers composés organiques à fonctions ?OH,COOH, NH2, ou autres, à l'aide de polyphosphates linéaires ou cycliques

Amino acids and other derivatives are condensed in aqueous solutions in the presence of linear or cyclic polyphosphates (or other anhydrides of P acids). The best results are obtained in slightly alkaline media (pH 7.5 to 9.5). The reaction, which has been studied at 70°C and at room temperature, proceeds with relative ease even at room temperature. In the case of the cyclic polyphosphates, trimetaphosphate gave the best results as compared with tetra- and hexametaphosphate, and among the linear polyphosphates used the yields grew with the average length of the chain. The significance of this method of condensation as a general method and also in the context of chemical evolution is discussed. The author suggests that one of the pathways leading to the peptide bond formation involves the intermediate formation of aminoacyl phosphates or polyphosphates by the nucleophilic attack of the carboxylate group of the amino acid on the phosphorus of a linear or cyclic P? O? P bond, giving rise to the labile mixed anhydride, and subsequent nucleophilic attack of the amino nitrogen of a molecule of the amino acid, or of the aminoacyl phosphate already produced, on the C of the mixed anhydride with displacement of phosphate or polyphosphate and formation of a peptide bond. Other pathways may also involve the intermediate formation of phosphoramidates which may result from the reaction of amino groups (or ammonia) with trimetaphosphate in alkaline medium. Linear and cyclic polyphosphates (which are known to be phosphorylating agents of the OH (alcoholic) function in aqueous solutions at pH's above 7) phosphorylate serine, ethanolamine and threonine in aqueous solutions at pH 8–10 with yields up to 25%.