Theoretical Study on the Activity of a-COOH and b-COOH of N-Phosphoryl Aspartic Acids

Many biological processes, such as signal transduction and protein synthesis are regulated by the phosphorylation and dephosphorylation of amino acid residues in the proteins1. In addition, formation of high-coordinate phosphoric intermediates is usually described as a key step in most of enzyme catalytic mechanisms2. Our previous work indicates that N-phosphoryl amino acids and peptides are chemically active species that characterize the bio-mimic reactivity3, which might be related to the …

Theoretical Study on the Activity of a-COOH and b-COOH of N-Phosphoryl Aspartic Acids

The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between a-COOH and b-COOH in phosphoryl aspartic acid was studied by theoretical study (Hartree-Fock and Density Functional methods) in this paper. The intermediates II containing five-membered ring were more stable than III with six-membered ring. While for intermediates III, the isomers with six-membered ring in apical-equatorial spanning arrangement were more stable than those with di-equatorial spanning arrangement. At B3LYP/6-31G** level, it was shown that transition states IV and V involving a-COOH or b-COOH group had energy barriers of DE = 58.67 kJmol-1 and 103.94 kJmol-1, respectively. These results were in agreement with the experimental data. So the a-COOH group was involved in form of the intramolecular penta-coordinate phosphoric-carboxylic mixed anhydride intermediates, but not b-COOH group.