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Does phosphoryl protonation occurs in aqueous phosphoesters solutions
1Laboratoire de Synthèse et Physico-Chimie de Molécules d'Intérêt Biologique, UMR-CNRS 5068, Université Paul Sabatier, 118 Route de Narbonne 31062 Toulouse Cedex 4, France.
Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
|November 1, 2005
Summary
This study reveals a novel positively charged phosphonium ion in acidic aqueous solutions of trimethylphosphate (TMP), dimethylphosphate (DMP), and diethylphosphate (DEP). This discovery has significant implications for understanding biochemical reactions involving phosphoryl groups.
Area of Science:
- Physical Chemistry
- Biochemistry
- Spectroscopy
Background:
- Phosphoryl groups are fundamental in biomolecules.
- Understanding ionization states of phosphate esters in solution is crucial for biochemical processes.
- Previous studies focused on the anionic and neutral forms of phosphate esters.
Purpose of the Study:
- To investigate the ionization of trimethylphosphate (TMP), dimethylphosphate (DMP), and diethylphosphate (DEP) in acidic aqueous solutions.
- To identify and characterize new ionic forms beyond the known anionic and neutral states.
- To explore the potential biochemical relevance of these findings.
Main Methods:
- Acidic titration in water.
- Raman (R) spectroscopy.
- Fourier transform infrared (FTIR) spectroscopy.
- Nuclear magnetic resonance (NMR) spectroscopy, including (31)P NMR titration.
- Deuteration experiments.
Main Results:
- Observed vibrational frequencies consistent with literature for PO(2)(-) and neutral forms.
- Identified a new, positively charged ionic form (phosphonium ion) at higher H(+) concentrations.
- Determined the pK of this phosphonium entity to be in the range of -2 to -4.
- Confirmed findings through (31)P NMR titration and deuteration experiments.
Conclusions:
- A novel phosphonium ion exists in acidic aqueous solutions of TMP, DMP, and DEP.
- The pK of this phosphonium ion suggests its potential role in concentrated biological environments.
- Further research on complex biomolecules like phospholipids, nucleic acids, and proteins is warranted to explore its biochemical significance.
- Physical-chemical parameters can influence the charge state and interactions of these ions.