Orientation of the peptide formation of N-phosphoryl amino acids in solution

The peptide formation of N-phosphoryl aminoacids with amino acids proceeds in aqueous solution withoutany coupling reagents. After being separated in sephadex gelcolumn, the phosphoryl dipeptides were analyzed by theelectrospray ionization tandem mass spectrometry (ESIMS/MS). The result demonstrates that phosphoryl dipeptideswere datected in all the reaction systems. It is found tkat theformation of N-phosphoryl dipeptides is oriented: theN-terminal amino acid residues of the N-phosphoryl dipep-tides are from N-phosphoryl amino acids, and the peptideelongation happened at the C-terminal. Only adipeptide, noβ-dipeptide, is formed in the N-phosphoryl dipeptides,showing that α-carboxylic group is activated selectively byN-pbosphorylation. Theoretical calculation shows that thepeptide formation of N-phosphoryl amino acids might hap-pen through a pentu-coordinate carboxylic-phosphoric in-termediate in solution. These results might give some clues tothe stlidy on the origin of proteins and protein