Gaucher disease is a group of lipid storage diseases in which the glycosphingolipid glucocerebroside accumulates in tissues because of deficiency of the enzyme glucocerebrosidase. Radioactively labelled glucocerebroside and the artificial fluorogenic substrate 4-methylumbelliferyl-β-d-glucopyranoside are commonly used for its diagnosis. We studied the use of a new chromogenic substrate, 2-hexadecanoylamino-4-nitrophenyl-β-d-glucopyranoside in cultured skin fibroblasts. The amount of reaction product, 2-hexadecanoylamino-4-nitrophenol, increased linearly with incubation time for at least 4 h and was proportional to the amount of fibro blast protein added up to 150 μg per incubation. The pH optimum was 4.8. The Km was 0.19 mmol/1. The mean activity of control cultured skin fibroblasts was 22.9 ± 5.4 nmol of product formed per mg fibroblast protein per hour under standard conditions. Cultured skin fibroblasts from patients with adult non-neuropathic Gaucher disease had reduced activity, 6.4 ± 2.4 nmol/mg/h or 28% of control activity. This compared well with mean enzyme activity in the same patients determined using the natural substrate, [14C] glucocerebroside: 28% of control activity. Heterozygotes had reduced activity with the new substrate.
All Science Journal Classification (ASJC) codes
- Clinical Biochemistry
- Biochemistry, medical