Physicochemical characterization of phosphinic pseudopeptides by capillary zone electrophoresis in highly acidic background electrolytes.
Phosphinic pseudopeptides (i.e., peptide isosteres with one peptide bond replaced by a phosphinic acid moiety) were analyzed and physicochemically characterized by capillary zone electrophoresis in the pH range of 1.1-3.2, employing phosphoric, phosphinic, oxalic and dichloroacetic acids as background electrolyte (BGE) constituents. The acid dissociation constant (pK(a)) of phosphinate group in phosphinic pseudopeptides and ionic mobilities of these analytes were determined from the pH dependence of their effective electrophoretic mobilities corrected to standard temperature and constant ionic strength of the BGEs. It was shown that these corrections are necessary whenever precise mobility data at very low pH are to be determined. Additionally, it was found that the ionic mobilities of the phosphinic pseudopeptides and pK(a) of their phosphinate group are affected by the BGE constituent used. The variability of migration behavior of the pseudopeptides can be attributed to their ion-pairing formation with the BGE components.
Koval
Dusan
D
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Kasicka
Václav
V
Jirácek
Jirí
J
Collinsová
Michaela
M
D002021:Buffers; D003999:Dichloroacetic Acid; D004573:Electrolytes / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000379:methods / Q000592:standards; D006863:Hydrogen-Ion Concentration; D008433:Mathematics; D015394:Molecular Structure; D009994:Osmolar Concentration; D019815:Oxalic Acid; D010455:Peptides / Q000032:analysis* / Q000737:chemistry; D010721:Phosphinic Acids / Q000737:chemistry*; D010756:Phosphoric Acids; D013696:Temperature
D002021:Buffers; D004573:Electrolytes; D010455:Peptides; D010721:Phosphinic Acids; D010756:Phosphoric Acids; D019815:Oxalic Acid; D003999:Dichloroacetic Acid; C030242:phosphoric acid