Trihexosylceramide alpha-galactosidase of human leucocytes

Trihexosylceramide, isolated from human kidney and labelled in the terminal galactose position by oxidation with galactose oxidase and reduction with sodium boro[3H]hydride, was used to study some of the properties of human leucocyte alpha-galactosidase. The enzyme was inactive in the absence of detergent. Of all the detergents tested a crude sodium taurocholate preparation displayed the greatest activity. The optimal detergent concentration varied from 2 to 4 mg/ml depending on the protein concentration and indicating that the enzyme activity was dependent on the protein/detergent ratio. Because of its influence in regulating enzyme activity, it is essential that care must be taken to ensure that the protein/detergent ratio of all incubation mixtures is kept relatively constant whenever the diagnosis of Fabry's disease is attempted.