title: Evaluation of a new continuous colorimetric method for determination of serum pseudocholinesterase catalytic activity and its application to a centrifugal fast analyser.
abstract: We report the evaluation of a new commercially available assay system for the determination of serum pseudocholinesterase (EC 3.1.1.8) catalytic activity, and its application to a kinetic analyser. The assay is based on the colorimetric method of Okabe et al. (Clin. Chim. Acta 80, 87-94 (1977]: choline, liberated from benzoylcholine by pseudocholinesterase, is oxidized by choline-oxidase (EC 1.1.3.17) to betaine with the simultaneous production of hydrogen peroxide, which oxidatively couples with 4-aminoantipyrine and phenol in the presence of peroxidase to yield a coloured compound with maximal absorbance at 500 nm. The procedure not only has the advantage of being continuous, colorimetric and totally enzymatic but also appears to be precise (between-day analysis gives coefficient of variation between 3.5 and 5.6%) and accurate; the results obtained from normal and pathological sera show excellent correlation with those obtained by the alternative procedures employing propionylthiocholine, acetylthiocholine and butyrylthiocholine as substrates.
mesh_terms: D002091:Butyrylcholinesterase / Q000097:blood*; D002151:Calorimetry / Q000379:methods; D002384:Catalysis; D002802:Cholinesterases / Q000097:blood*; D003992:Dibucaine; D006801:Humans; D007202:Indicators and Reagents; D011933:Reagent Kits, Diagnostic; D013860:Thiocholine / Q000031:analogs & derivatives; D014461:Ultracentrifugation / Q000379:methods
chemical_list: D007202:Indicators and Reagents; D011933:Reagent Kits, Diagnostic; C009063:propionylthiocholine; D013860:Thiocholine; D002091:Butyrylcholinesterase; D002802:Cholinesterases; D003992:Dibucaine