The Investigation of Interaction Competition Between ATP and DIPP-Ala, Boc-Ala, or Ala by ESI-MS/MS and Theoretical Calculation

Abstract

The interactions between ATP and N-(O,O-diisopropyl) phosphoryl-L-alanine (DIPP-Ala), N-(tert-butoxycarbonyl)-L-alanine (Boc-Ala), or L-alanine (Ala) were investigated by electrospray ionization tandem mass spectrometry (ESI-MS/MS). The non-covalent complexes between ATP and Boc-Ala or DIPP-Ala were observed, while the complex between ATP and Ala was not found in the mass spectra. The affinity of DIPP-Ala for ATP was confirmed to be stronger than that of Boc-Ala by competition experiment. Through molecular modeling calculations, it was found that the non-covalent complexes were stabilized by intermolecular hydrogen bonds, and the affinity sequence for ATP was DIPP-Ala > Boc-Ala > Ala by comparing their binding energy, −35.407 kcal/mol, −15.634 kcal/mol, −6.555 kcal/mol, respectively. The results implied that a phosphoryl group was a very important functional group to provide an interaction site between amino acids and ATP, and that N-phosphoryl amino acids can be used as a good model of protein in the studies of molecular recognition of ATP.

Keywords:

• ATP
• ESI-MS/MS
• mini-model of protein
• molecular dynamic simulation

Acknowledgments

The authors would like to thank the National Natural Science Foundation of China (No. 20572061, 20672104, 20732004), the Ministry of Science and Technology (No. 2006DFA43030), the Chinese Ministry of Education, and Zhengzhou University for financial support.

Notes

*Atom number shown in Figure 3.

*Calculated from Equation (1).