Diagnostic test for Niemann-Pick disease

摘要

An artificial substrate consisting of a 2-alkanoylamino-4- nitrophenyl phosphorylcholine hydroxide is used for determining the sphingomyelinase activity in an extract of human cells or tissues by incubating the substrate together with the extract, whereby sphingomyelinase-catalyzed hydrolysis of the substrate into the corresponding 2-alkanoylamino-4- nitrophenol and phosphorylcholine takes place in an amount proportional to the sphingomyelinase activity in the extract. Alkalinization of the 2- alkanoylamino-4-nitrophenol thereby produced to convert it into the alkali salt results in the development of a bright yellow color whose intensity is proportional to the amount of the substrate that has been hydrolyzed. Measurement of the intensity of the yellow color, for example, by means of a simple colorimeter or photometer, provides an accurate indication of the sphingomyelinase activity in the extract.