title: Assay of serum cholinesterase with succinylcholine and propionylthiocholine as substrates.
abstract: Serum cholinesterase (E.C. 3.1.1.8) was assayed with succinylcholine as a substrate. The reaction was coupled with choline oxidase and peroxidase in the presence of 4-aminoantipyrine and phenol to produce a red quinone dye that was measured spectrophotometrically. The method requires 25 microliter of sample in a total volume of 1.0 ml. The mean activity for 35 adults of the usual genotype was 74.4 +/- 28 U/l (range 24-125 U/l). Succinylcholine-sensitive individuals had activities below 18 U/l. The same serum samples also were assayed with propionylthiocholine as a substrate. Activities with the two substrates showed a coefficient of correlation of 0.980 (n = 68). However, the method using propionylthiocholine showed more overlap between the activities of succinylcholine-sensitive and insensitive individuals. Assay with succinylcholine thus may offer a more effective method of screening for sensitive individuals, since some escape detection by conventional genotyping with dibucaine and fluoride.
mesh_terms: D000429:Alcohol Oxidoreductases; D002794:Choline / Q000031:analogs & derivatives*; D002802:Cholinesterases / Q000097:blood* / Q000235:genetics; D002863:Chromogenic Compounds / Q000032:analysis; D005838:Genotype; D006735:Horseradish Peroxidase; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D011809:Quinones / Q000032:analysis; D012016:Reference Values; D013053:Spectrophotometry; D013390:Succinylcholine; D013860:Thiocholine / Q000031:analogs & derivatives*
chemical_list: D002863:Chromogenic Compounds; D011809:Quinones; C009063:propionylthiocholine; D013860:Thiocholine; D000429:Alcohol Oxidoreductases; C019888:choline oxidase; D006735:Horseradish Peroxidase; D002802:Cholinesterases; D013390:Succinylcholine; D002794:Choline