title: A facile enzymatic technique for the estimation of nanomolar concentrations of N-phosphonacetyl-L-aspartic acid in plasma.
abstract: A sensitive radiometric enzyme-inhibition assay is described for the determination of N-phosphonacetyl-L aspartic acid (PALA, NSC-224,131) in plasma. The assay is based on the inhibition of PALA, at low concentrations of the competitive co-substrate carbamyl phosphate, of L-aspartate transcarbamylase prepared from mouse spleen. The assay responds with good reproducibility and in a proportional way to concentrations of PALA over the range of 2-20 nM; as such, it represents a 100-fold increase in sensitivity over existing methodologies. The applicability and pertinence of this assay to long-term pharmacokinetic studies with PALA is demonstrated by the one month persistence of nanomolar concentrations of PALA in the plasma of mice treated with a single dose of the drug.
mesh_terms: D000818:Animals; D001221:Aspartate Carbamoyltransferase / Q000378:metabolism; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000097:blood; D002221:Carbamyl Phosphate / Q000494:pharmacology; D002250:Carbon Radioisotopes; D006801:Humans; D007700:Kinetics; D051379:Mice; D008832:Microchemistry; D009943:Organophosphorus Compounds / Q000097:blood*; D010746:Phosphonoacetic Acid / Q000031:analogs & derivatives / Q000097:blood*; D011865:Radioisotope Dilution Technique; D013154:Spleen / Q000201:enzymology
chemical_list: D002250:Carbon Radioisotopes; D009943:Organophosphorus Compounds; D001224:Aspartic Acid; D002221:Carbamyl Phosphate; C013195:sparfosic acid; D001221:Aspartate Carbamoyltransferase; D010746:Phosphonoacetic Acid